Documents published in 2020 : Scipedia

Study on a Proper Repair Cycle of Finishing Materials in Condominiums
T. Ide, H. Hamasaki, Y. Soga

DBMC (2020).

Abstract
In this paper, we discussed the concept for appropriate repair period for finishing materials of reinforced concrete structures. We investigated the actual building repair cycle, the progress of carbonation of concrete, and the adhesion strength of various finishing coating. In addition, we carried out 10-years exposure test of concrete with various finishing to evaluate the progress of carbonation and the degree of deterioration of the finish coating material. From these results, we showed the possibility of extending beyond the current repair cycle.
Abstract
In this paper, we discussed the concept for appropriate repair period for finishing materials of reinforced concrete structures. We investigated the actual building repair [...]
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Performance and Durability of Adhesive Tapes for Building Applications. From Product Documentation to Scientific Knowledge (and Back Again)
M. Sletnes, S. Frank

DBMC (2020).

Abstract
Adhesive tapes are used extensively in both new buildings and renovation projects in order to achieve airtight building envelopes and energy efficient buildings. It is important to be able to reliably predict whether these adhesive solutions are durable. In our roles as both a research institute and a national approval body for building materials, SINTEF have been performing product evaluations and testing of adhesive tapes for 10 years. During this time, we have tested the durability of more than 30 different tapes on a variety of substrates commonly used in the building industry. After systemising and analysing this data, we have gained valuable insight into the factors governing the durability of adhesive tapes for the construction market. In this paper we share our findings and discuss how we intend to utilise the new knowledge in the design of further scientific experiments in the field.
Abstract
Adhesive tapes are used extensively in both new buildings and renovation projects in order to achieve airtight building envelopes and energy efficient buildings. It is important [...]
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Seismic Performance of RC Moment Frame Structures Made with EAF Slag Aggregates
F. Faleschini, M. Zanini, K. Toska

DBMC (2020).

Abstract
Sustainability in the construction industry is becoming everyday more a major issue in todays world. To accomplish sustainability goals, adopted also by the Agenda 2030 of the United Nations, wide research has been carried out in the past years. Among this, the use of recycled aggregates has been proven to be promising both in terms of sustainability and material properties. Electric Arc Furnace (EAF) concrete has demonstrated a significant increase in mechanical properties when compared to natural aggregates (NA) ones. However, the mechanical properties enhancement is accompanied by an increase of its specific weight and the overall effects of its use in RC structures subjected to dynamic loads, has not been investigated yet. The present study aims to investigate the seismic reliability of reinforced concrete frame buildings made with EAF in comparison to the same structural configurations made with NA concrete, considering three different configurations (3-, 6- and 9- story building type) designed considering ordinary concretes made with natural aggregates.
Abstract
Sustainability in the construction industry is becoming everyday more a major issue in todays world. To accomplish sustainability goals, adopted also by the Agenda 2030 of [...]
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Effects of Finishing Materials against Carbonation and Corrosion Condition of Model Building Exposed to Outdoor Conditions for 30 Years
K. Matsuzawa, O. Senbu, K. Imamoto, C. Kiyohara, K. Etchuya, K. Nemoto

DBMC (2020).

Abstract
A model building made out of concrete block specimens whose surfaces were coated with various finishing materials was constructed for the outdoor exposure test. After 30 years of outdoor exposure, the deterioration of finishes and their carbonation and corrosion inhibition effects were investigated. As a result, the following conclusions were obtained: Though the deterioration levels differed depending on their types and thickness, all finishing materials showed some kind of deterioration after 30 years‘ long-term outdoor exposure. The progress of carbonation and corrosion are prevented when the surface is coated with finishing materials of sufficient thickness or waterproof effect. Regarding the relationship between corrosion depth and carbonation depth, corrosion is initiated after the carbonation front reaches the area. It usually takes a while to initiate corrosion in the carbonated area, not immediately after the carbonation reaction. When the concrete surface is properly coated with finishing material, corrosion may not be initiated in non-carbonated area in concrete where the pH level is not lowered.
Abstract
A model building made out of concrete block specimens whose surfaces were coated with various finishing materials was constructed for the outdoor exposure test. After 30 years [...]
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Performance Based Specification of Wood – Project CLICKdesign
E. Suttie, C. Brischke, E. Hansson, S. Fortino, J. Sandak, M. Kutnik, G. Alfredsen, C. Lucas, E. Vieillemard

DBMC (2020).

Abstract
This paper introduces the ForestValue research project CLICKdesign – delivering fingertip knowledge to enable service life performance specification of wood. The consortium is working on a primary innovation to move from the complex, fragmented and general to the easy-to-use, consolidated and specific by provision of a digital tool for specifiers. Other materials tackle this and provide designers and architects with software. The specification of performance of wood products is complex and fraught with inconsistency and requires use of multiple platforms for data, experience, standards and national recommendations. CLICKdesign will provide a tool that has within it the decades of research, the complexity of the standards specification systems and the variation of approach due to tradition, materials and culture across Europe and beyond. A simple tool for nonexpert public users will be available as well as a tool accessible to professional users that will be refined with industry to ensure relevancy and accelerate uptake and use.
Abstract
This paper introduces the ForestValue research project CLICKdesign – delivering fingertip knowledge to enable service life performance specification of wood. The consortium [...]
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Effect of the Type of Concrete with Mineral Additions on the Reinforcement Corrosion Induced by Chlorides - Analysis in the Same Mechanical Strength Class
A. Oliveira, O. Cascudo, A. Castro, H. Carasek

DBMC (2020).

Abstract
The environment in which the concrete structure is inserted has a great influence on its durability and its service life. Thus, the present work aims to study of the performance of 5 types of concretes of same compressive strength (35 MPa at the age of 28 days) and considers kinetic and thermodynamic aspects of the corrosion induced by chlorides. The 5 types of concretes studied were produced with the use of mineral additions in partial replacement on cement mass (10% of silica fume, 30% of fly ash and 20% of metakaolin), besides the control situation (without mineral addition). The water-to-cementitious materials ratio was different for the concretes ranging from 0.30 to 0.55. Specifically, for the concrete with fly ash, two water/binder ratios were studied (0.30 and 0.40) with the goal of verifying if there are or not significant differences on properties of corrosion with little change of water quantity in the mix. The chloride attack consisted by 308 days (44 weekly cycles) in immersion in aggressive solution rich in chlorides and subsequent drying in a laboratory environment. During this period, the corrosion potentials (Ecorr) and corrosion rate (icorr) from polarization resistance (Rp) of steel bars were monitored. As a general result, it was possible to compare the performance of concretes at the same class of compressive strength to denote which systems have the longest durability in view of attack by chloride. The results have shown that the concretes produced with mineral additions did not show steel bar corrosion, thus configuring major service life for them. Control concrete presented depassivation of reinforcing steel, Ecorr more electronegative and higher icorr over time.
Abstract
The environment in which the concrete structure is inserted has a great influence on its durability and its service life. Thus, the present work aims to study of the performance [...]
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Implementing a Framework for Qualitative Assessment of New Technical Solutions: A Case Study on CLT
C. Tengberg, C. Hagentoft

DBMC (2020).

Abstract
New technical solutions are introduced at a fast pace in the Swedish construction industry, mainly driven by issues concerning costs and productivity. These new technical solutions can comprise new materials, new goods, new designs but also new processes. The record of accomplishment when introducing new technical solutions in the industry is not unproblematic and serial failures of different new technical solution have occurred. In an earlier interview study exploring introduction of new technical solutions in the Swedish construction industry, a common lack of thorough methods for evaluation of new solutions was identified. To address this issue, a case study was performed, exploring a method of evaluation with respect to building physics while implementing a cross laminated timber frame in a multifamily building. The case study uses a framework of assessment with focus on building physics. This paper presents the findings from the case study focusing on how evaluation of a new technical solution with respect to building physics is performed, together with an evaluation of the method, using the experiences of the participants in the case study.
Abstract
New technical solutions are introduced at a fast pace in the Swedish construction industry, mainly driven by issues concerning costs and productivity. These new technical [...]
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Assessment of Reasons behind and Level of Destruction of Aquatic Supports in a Hydraulic Ash Removal Bridge
T. Błaszczyńsk, A. Łowińska-Kluge

DBMC (2020).

Abstract
The presented article describes a case of damage to concrete in the aquatic supports of a hydraulic ash removal bridge in a power plant. Carrying out an assessment of the causes of concrete damage, as well as determining the possibility of the occurrence of corrosive phenomena within it, and thus, consequently, predicting the durability of the building structure and selecting, on its basis, a proper repair-renovation procedure, required a series of essential studies and analyses to be carried out. Therefore, in the analyzed case, a complex study was carried out on the structure as well as tests on samples of concrete cut out, in the form of core drillings, from the damaged structure (among others: macroscopic, microscopic SEM, XRD, DTA, chemical analyses). Based on these studies, the types of corrosion responsible for the analyzed damage were determined.
Abstract
The presented article describes a case of damage to concrete in the aquatic supports of a hydraulic ash removal bridge in a power plant. Carrying out an assessment of the [...]
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Possibilities of Reducing Energy Costs in the Life Cycle of Office Buildings
E. Plebankiewicz, K. Zima, D. Wieczorek

DBMC (2020).

Abstract
Buildings absorb energy at every stage of the life cycle. The paper analyses the phases of the life cycle of an office building indicating the possibilities of reducing energy consumption. In particular, attention was paid to the most energy-intensive phase, that is the use phase. Both simple actions and more advanced solutions allowing to reduce the energy demand of a building during the use phase are characterized. For an exemplary office building, life cycle costs were calculated taking into account selected solutions improving energy efficiency.
Abstract
Buildings absorb energy at every stage of the life cycle. The paper analyses the phases of the life cycle of an office building indicating the possibilities of reducing energy [...]
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A Probabilistic Model for the Evolution of Porous Structure Caused by Solid-Phase Precipitation/Dissolution within Building Materials.
X. Xiang, M. Fekri

DBMC (2020).

Abstract
Saline intrusion is a critical issue in building material because of the severe damages caused by the salt precipitation/dissolution process, especially for the porous material, which has good connectivity. When porous material is exposed to aggressive ambient, the pore structure, not only porosity but also pore size distribution, will be altered by salt precipitation/dissolution. As one of the most significant characteristics in the porous material, pore size distribution is always paid much attention in many literatures. However, a quantitative and practical determination method is still absent. This work aims to establish a probabilistic model to investigate the pore size distribution induced by solid-phase precipitation/dissolution. First, a lognormal distribution is proposed for the simulation of initial pore size distribution tested by the MIP method. Then we develop a probabilistic-based porous network to represent the evolution of microstructure due to precipitation/dissolution. To this end, two different transformation models are constructed to interpret the relation between initial pore radius and modified pore radius before and after precipitation/dissolution. With this probabilistic-based porous network, we could illustrate the precipitated profiles that evolve near the capillary interface during the salt precipitation/dissolution process for a given porosity and water saturation degree. Such a method could be used to interpret the mechanism of the local precipitation/dissolution process in pore scales, which cannot be implemented by experimental measurements.
Abstract
Saline intrusion is a critical issue in building material because of the severe damages caused by the salt precipitation/dissolution process, especially for the porous material, [...]
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Effect of Selected Moisture Reference Year on the Durability Assessment of Wall Assemblies under Future Climates
S. Sahyoun, H. Ge, C. Aggarwal, M. Defo, T. Moore

DBMC (2020).

Abstract
Hygrothermal simulations are commonly used to evaluate the moisture damage risk of building envelopes over the long-term. For such assessment to be accurate, a proper selection of representative climate data is required. A common method is the selection of a moisture reference year from a set of available long-term climate data. For instance, the IRC-led research consortium MEWS (Moisture Management of Exterior Wall Systems) developped the Moisture Index (MI) approach, which consists of a wetting and a drying function. Therefore, the reference year selection would be based on the MI ranking. ASHRAE 160 is adopting a procedure named “the severity index” for the selection of moisture reference year. Combining climate loads and durability criteria, this method allows to select more “severe” weather years, thus providing a more representative ranking of the weather data. The objective of this paper is two-fold. First, to compare the selection of the moisture reference year based on two different approaches for both historical and future climate loads. Second, the effect of chosen representative years is evaluated and compared to long-term simulation periods (of 31-years) based on the durability of building assemblies. The methodology includes hygrothermal simulations of two different types of wall assemblies located in three different Canadian cities under a changing climate. In general, higher mold index values were obtained by the long-term simulation and MRYs using Isev. Comparing the results of different models under future climates, the three methods were in good agreement, except for a brick wall facing WDR in Ottawa and Vancouver. This might be due to the Isev correlations were developed based on a north-facing stucco wall. In addition, for a north-facing wall, an extremely low mold index was predicted for Vancouver, compared to WDR direction. Thus, considering a north-facing wall as a criterion for performance evaluation might misrepresent the reality in some locations. Hence, both WDR and North orientations should be considered. A further study will be carried out to investigate the performance evaluation of Isev method for different types of wall systems and orientations.
Abstract
Hygrothermal simulations are commonly used to evaluate the moisture damage risk of building envelopes over the long-term. For such assessment to be accurate, a proper selection [...]
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Modernization of Housing Estates Towards Sustainable Development: What do Housing Estate Managers Provide, What do the Users See?
A. Ostańska

DBMC (2020).

Abstract
Modernizing multi-family residential estates in operation for about 40 years is a multifaceted and complex process. In Poland, these assets cannot be considered "degraded" yet, they are not an obvious object of deep retrofit actions. The literature on the subject and the author’s own research confirm that the management of Polish housing estates is carried out with the focus on current repairs and improving energy efficiency by insulating the buildings’ envelopes. Poland lacks long-term programs to implement retrofitting actions based on the analysis of both social and technical needs and aimed at improving the estate’s sustainability parameters. The author puts forward an original approach to the programming of sustainable housing stock retrofit based on the PEARS model (PeopleEnvironment-Actions-Resources-Sociology). The paper focuses on the social research part of the model and presents the case-based analysis – the results of the recurring survey conducted to provide input for sustainable planning of the estate improvements. The paper is a summary of over ten years of research and studies on practices of maintenance of infrastructure and buildings, changing user needs, and user opinions on the possible directions towards sustainable housing.
Abstract
Modernizing multi-family residential estates in operation for about 40 years is a multifaceted and complex process. In Poland, these assets cannot be considered "degraded" [...]
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Analysis of Steel Bars in Corrosion Process after 70 Years of Natural Aging.
F. Schmoeller, M. Lima, S. Silva

DBMC (2020).

Abstract
Reinforced concrete structures are commonly used in civil engineering. However, the number of deteriorations in these structures is increasing, especially problems related to steel corrosion. Also, according studies, corrosion is responsible for about 3.5 % of annual GDP with recovery costs in world. Thus, this study analyzed the corrosion of steel bars at 70-year-old, which are in corrosion process by natural aging. Tests were performed to analyze the bars microstructure, using SEM and EDS, as well as analysis of the current mechanical characteristics, with tensile test. Through SEM, it was possible to measure the layer of the corrosion products formed at the samples edge, and to observe the fragility of this region, with the presence of several microcracks. EDS test contributed to verify the oxygen difference from the nucleus until to the specimen edge. It was possible to notice that in the edge, presence of oxygen is much greater. In the mechanical tests, by the tensile test, the samples do not reach the minimum elongation and the limit of resistance prescribed in the standard. Thus, it is believed after 70 years of natural aging, the samples are in advanced process of corrosion, with edges worn out, and no comply with the minimum mechanical requirements.
Abstract
Reinforced concrete structures are commonly used in civil engineering. However, the number of deteriorations in these structures is increasing, especially problems related [...]
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Experiences from Interior Super Insulation of a Brick Wall from the 1800s
P. Johansson, P. Wahlgren

DBMC (2020).

Abstract
Many brick buildings in Sweden today face a large need for renovation measures to prolong their service life and make other uses possible. Conventional thermal insulation materials, such as fibre glass and EPS, demand a thick layer of insulation to reach the energy targets. Super insulation materials, such as vacuum insulation panels (VIP) and aerogel blankets (AB), are thermal insulation components with a 3-10 times higher thermal resistance than conventional insulation materials. In this study, the effect of interior insulation using super insulation materials is investigated, using experiences from a case study in a brick wall from the 1800s. Earlier research has shown that interior insulation decreases the drying-out capacity of an exterior wall and increases the risk for freeze-thaw damages in brick walls. The case study building is an industrial building from 1896 with 470 mm homogeneous brick masonry walls insulated with both aerogel insulation and with vacuum insulation panels. Six heat flux sensors were installed in the wall and used to evaluate the thermal resistance of the wall with and without insulation. The initial measurements showed that the rate of water flow in the bricks is approximately three times higher than that in modern bricks. The average calculated U-value was reduced by 70% for the AB and 81% for the VIP layers, while measurements at the three occasions gave a reduction of 72-83% for the AB and 72-84% for the VIP layers, i.e. in the same order of magnitude.
Abstract
Many brick buildings in Sweden today face a large need for renovation measures to prolong their service life and make other uses possible. Conventional thermal insulation [...]
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Various Factors of Water Entry and Penetration Through Water Proofing Layer in Wooden Wall Assembly
H. Saito, M. Miyamura

DBMC (2020).

Abstract
Rainwater entry and penetration through a waterproofing layer, such as external finishing and sheathing membrane, should be avoided to prevent moisture damage to a wooden wall assembly. However, housing warranty insurance organizations in Japan have reported that deterioration in some wall assemblies was caused by rain penetration, and severely damaged walls were detected in airtight and insulated building envelopes. This paper presents various factors of water entry and penetration of the waterproofing layers in wooden wall assemblies in terms of practical situations, as a part of a research project to reveal the risk of water and moisture accumulation in collaboration with government and industries in Japan. Several experimental works using mock-up specimens replicating a part of the wall assembly were carried out. As for external finishing, the water intrusion was observed not only at the joints but also at the bottom of vented cavities. Although these minor defects must be prevented by proper design and site work, it is difficult to avoid them completely through the construction process and period of use. Indeed, the extent of water entry was affected by various factors such as wall configuration, exposure conditions and so on. Experimental results suggested that various factors, including detail of interface and quality of materials, should be considered to assess service life prediction by hygrothermal analysis.
Abstract
Rainwater entry and penetration through a waterproofing layer, such as external finishing and sheathing membrane, should be avoided to prevent moisture damage to a wooden [...]
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Biodegradable Polymers on Cementitious Materials
J. García-González, P. Lemos, A. Pereira, J. Pozo, M. Guerra-Romero, A. Juan-Valdés, P. Faria

DBMC (2020).

Abstract
Nowadays the sustainability and safety requirements of structures inspire the study of new self-healing materials and preventive repair methods on cementitious elements. To achieve this undertaking, this research replaces widely employed synthetic polymers by biodegradable ones as consolidants and water-repellents, and assesses the protection and consolidation effect of biopolymers (obtained by using waste biomass of mixed microbial cultures from polyhydroxyalkanoates production processes) as eco-friendly healing agents by analysing the water absorption of two kind of materials. The first group of samples are cement mortar specimens whose external surface has been treated with biopolymer products and subsequently evaluated by water drop absorption test. The second group of samples are cement mortar specimens formulated with biopolymer products included in its mixing water and later the waterproofing efficiency is analysed by capillary water absorption tests. The water absorption behaviour of both kind of samples shows a potential improvement of cementitious elements durability, since water absorption results have decreased for treated samples in comparison with untreated ones.
Abstract
Nowadays the sustainability and safety requirements of structures inspire the study of new self-healing materials and preventive repair methods on cementitious elements. To [...]
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Two-Part Bio-Based Self-Healing Repair Agent for Cement-Based Mortar
M. Tezer, Z. Bundur

DBMC (2020).

Abstract
Factors affecting durability of concrete structures are generally associated with each other. Due to its brittle nature, concrete can crack under stress and these cracks are one of the main reasons for a decrease in service life in concrete structures. Therefore, it is crucial to detect and recover microcracks, then to repair them as they were developed to wider cracks. Recent research in the field of concrete materials suggested that it might be possible to develop a smart cement-based material that is capable of remediate cracks by triggering biogenic calcium carbonate (CaCO3) precipitaton. This paper summarizes a study undertaken to investigate the self-healing efficiency of Sporosarcina pasteurii (S. pasteurii) cells immobilized on both diatomaceous earth and pumice, to remediate flexural cracks on mortar in early ages (28 days after mixing). To obtain a two-phase bio additive, half of the minerals were saturated with a nutrient medium consisting of urea, corn-steep liqueur(CSL) and calcium acetate and the cells with immobilized to the other half without nutrients. Screening of the healing process was done with ultrasonic pulse velocity (UPV) testing and stereomicroscopy. With this approach, the cracks on mortar surface were sealed and the water absorption capacity of the so-called self-healed mortar decreased compared to its counterpart cracked mortar samples.
Abstract
Factors affecting durability of concrete structures are generally associated with each other. Due to its brittle nature, concrete can crack under stress and these cracks are [...]
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Large Scale Laboratory and Field Tests of Aerogel Renders
J. Frick, N. Sakiyama, M. Stipetic, H. Garrecht

DBMC (2020).

Abstract
Within the framework of the European project Wall-ACE a large-scale laboratory test (EOTA-Wall Test) was performed. Additional a test field in Switzerland was equipped with six different aerogel renders by the project partner AGITEC. Laboratory walls and test field were equipped with sensors to monitor in real-time climate, heat flux, temperature, relative humidity, and at the laboratory tests additional material moisture. The data allow calculating U-values and material parameters as well as drying behaviour of render and substrate. During and after the artificial weathering in laboratory the renders were subjected to visual inspection and mechanical adhesion tests. The performance of the aerogel renders will be assessed and compared with results on conventional insulation renders.
Abstract
Within the framework of the European project Wall-ACE a large-scale laboratory test (EOTA-Wall Test) was performed. Additional a test field in Switzerland was equipped with [...]
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Deterioration Prediction Model of Multi-Layer Coating Material and its Reference Service Life Evaluation in Terms of Carbonation Control Effect
K. Etchuya, K. Imamoto, C. Kiyohara

DBMC (2020).

Abstract
In this paper, authors propose a method to predict deterioration of exterior finishes using Markov Chain Model based on field survey results on cracks of exterior finishes of existing RC buildings. There existed correlation between degradation of finishing and carbonation progress. Authors propose the service life prediction approach to focus on the carbonation suppression effect into the concrete considering progress of exterior finish deterioration.
Abstract
In this paper, authors propose a method to predict deterioration of exterior finishes using Markov Chain Model based on field survey results on cracks of exterior finishes [...]
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Compressive Strength Improvement and Water Permeability of Self-Healing Concrete Using Bacillus Subtilis Natto
N. Huynh, K. Imamoto, C. Kiyohara

DBMC (2020).

Abstract
In recent years, many projects have been carried out to enhance the durability of concrete structure from the influence of cracks. Generally, managing cracks should be a rather preventative method for sustainable development. Based on that, Bacillus subtilis natto - a local bacterium in Japan was found to have the ability to form CaCO3, which can be used as healing materials for cracks in the concrete structure. The bacterial biomineralization immobilized in lightweight aggregate was studied to improve the compressive strength by healing the cracks and densifying the structure. Moreover, as an essential parameter for durability enhancement, the water permeability of self-healing concrete through a water-flow system was carried out. Experimental results on the behavior of the materials indicate that Bacillus subtilis natto could lead the compressive strength to 40 % higher than the controls. Promising result in preventing the water through the cracks confirmed the self-healing effect with more potential in larger-scale.
Abstract
In recent years, many projects have been carried out to enhance the durability of concrete structure from the influence of cracks. Generally, managing cracks should be a rather [...]
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Drying Potential of Wood Frame Walls Subjected to Accidental Water Infiltration
M. Steeman, N. Bossche, K. Calle

DBMC (2020).

Abstract
Wood frame construction is the most widespread building method. In Belgium the number of wood frame buildings has grown in the last years: in 2018 over 10% of all new built dwellings were wood frame buildings. This increase can be partly attributed to the growing attention for energy performant buildings with a low environmental impact. In contrary to masonry construction, wood frame is more vulnerable to moisture problems, mould growth and wood rot. An important risk is water infiltration through imperfections in the building envelope as a result of driving rain. Therefore it is important for the design to be resilient and allow drying without consequential damage. To analyze the drying potential, an experimental set-up with 8 wood frame compartments was built. The compartments differ in the type of insulation material (mineral wool or cellulose) and the type of vapour retarder (OSB or smart vapour retarder) that were used. In this way 4 types of compartments were obtained, each having a different combination of insulation and vapour retarder. Of each combination there are 2 identical compartments. This allows to insert water in one of both, to mimic rain water infiltration from the outside into the compartment. Temperature, relative humidity and moisture content were measured on different locations in the construction (in total 92 sensors). In this way, the hygrothermal performance of the compartments with and without water infiltration can be analyzed, as well as the drying rate.
Abstract
Wood frame construction is the most widespread building method. In Belgium the number of wood frame buildings has grown in the last years: in 2018 over 10% of all new built [...]
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Evaluation of Socio-economic Impacts of Incidents on the Railway Infrastructure
V. Hromádka, J. Korytárová, E. Vítková, T. Funk, H. Seelmann

DBMC (2020).

Abstract
Evaluation of the economic efficiency of investment projects in transport infrastructure in the Czech Republic is methodically based on the Departmental Methodology of the Ministry of Transport. Economic cash flows, generated in accordance with the CBA principles, are modelled within this methodology on the basis of the evaluation of socio-economic impact of individual projects. In the case of the railway infrastructure constructions, the socio-economic impacts used by the methodology do not include benefits associated with increasing safety and reliability of the railway infrastructure network due to new security systems implementation. Determination of socio-economic impacts associated with specific types of incidents on the railway which are caused by insufficient railway infrastructure security and which could be eliminated by the implementation of the higher-level signaling equipment forms the subject of the research. The research is based on the analysis of a database of incidents occurring on the railway in the Czech Republic in the 2009 – 2018 period, which describes the basic impacts associated with a particular incident. Statistical data on the railway infrastructure is also used to determine the impact of incidents in addition to the database. The key outcomes of the research are the determination of methodological steps for the evaluation of the impacts of incidents on the railway and a case study for their verification. Future research will focus on making evaluation of the abovementioned benefits more detailed. Research outcomes will improve decision-making process on selection and financing of the projects related to railway infrastructure safety for their future implementation.
Abstract
Evaluation of the economic efficiency of investment projects in transport infrastructure in the Czech Republic is methodically based on the Departmental Methodology of the [...]
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Assessing Water Resistance and Surface Properties of ETICS
G. Borsoi, J. Parracha, P. Caiado, I. Flores-Colen, A. Dionísio, R. Veiga

DBMC (2020).

Abstract
External Thermal Insulation Composite Systems (ETICS) contribute significantly to building energy efficiency by increasing thermal insulation, correcting thermal bridges and reducing interior water condensation. Additionally, these solutions protect the structure and thus enhance the durability of the building. The use of ETICS remarkably increased in the last three decades also due to the introduction of new international and national regulations on building energy efficiency (e.g. EU Directive on the Energy Performance of Buildings). ETICS are constantly exposed to weathering (e.g. wind, rain, sun light) and anthropic factors (e.g. graffiti, environmental pollutants), which can lead to cracks, biocolonization and stains and thus affect ETICS durability. However, international technical documents on the evaluation of the effectiveness and durability of ETICS do not consider the possible synergies between these factors, which can trigger and speed up multiple biological, mechanical and chemical degradation processes. With the aim of filling this gap, this paper focused on the water resistance and surface properties of several ETICS surface coatings, verifying possible connections between these factors. The moisture transport properties (capillary water absorption, water vapour permeability, and drying kinetics) and surface properties (colour, brightness and roughness) of some commercially available ETICS were tested. This study is part of a wider research project (WGB_Shield: resistance for water, graffiti and biocolonization of external thermal insulation systems) that aims at the development of ETICS with improved durability in urban environment.
Abstract
External Thermal Insulation Composite Systems (ETICS) contribute significantly to building energy efficiency by increasing thermal insulation, correcting thermal bridges and [...]
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Durability Assessment of GFRP Rebars Exposed to High pH-Seawater
A. Emparanza, C. Morales, J. Palacios, F. Caso, A. Nanni

DBMC (2020).

Abstract
There is a continued process to implement innovative materials to enhance the sustainability and durability of the built infrastructure. Technologies developed over the last two decades have facilitated the use of glass fiber reinforced polymer (GFRP) composites as internal reinforcement bars (rebars) for concrete structures, which have proven to be an alternative to traditional steel reinforcement due to significant advantages, such as magnetic transparency and, most importantly, corrosion resistance, equating to durability and structural life extension. This study evaluates the durability of three different available and most commonly used GFRP rebar types, based on exposure to aggressive environments, such as those experienced in coastal areas. For that, the specimens were expose to high pH seawater solution (that simulates the alkalinity of the concrete exposed to seawater), at 60 ºC for different periods of time: 45, 90, and 180 days. The durability of these GFRP rebars was assessed by testing four different physio-mechanical properties, including: tensile strength, elastic modulus, and transverse and horizontal shear strength. Preliminary results show that the resilience of the GFRP rebars after being exposed to high pH seawater at high temperature, varies considerably among the three different types. The tensile strength was the most affected physio-mechanical property.
Abstract
There is a continued process to implement innovative materials to enhance the sustainability and durability of the built infrastructure. Technologies developed over the last [...]
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Client’s Expectations vs Contractor’s Pricing. Fair Prices or Bid Rigging
H. Anysz, A. Foremny

DBMC (2020).

Abstract
The road construction sector is a specific part of the construction industry. It happens very rarely that a section of a road is financed also by a private entity. The other factor distinguishing it – is a significant value of road construction contracts. The Client’s estimates of the value of the prospective contracts have to be based on the market prices in case of public procurement. However, this market is dominated by public orders. There is no comparison to the value of works ordered on the private part of the construction market, which is found more efficient by economists. Widely applied the “design and build” type of orders make the comparisons of the unit prices more difficult. The huge differences between the Client’s estimates and the winning prices in the road construction public tender procedures are the bases of speculations about the fairness of the procedures. These differences can have a varied origin. There are several reasons for them e.g. varied contractor’s risk, the size of the structure, type of order, the dynamics of the road construction market. Nevertheless, fraudulent practices can make the winning price much higher than the Client’s estimate. The article is an attempt to finding the limit i.e. what part of these differences can be explained by fair, market reasons. If the found limit is exceeded, it should make the Client carefully consider the offers placed. The analysis is based on collected data concerning almost 400 tender procedures for the sections of roads in Poland in 2014-2017.
Abstract
The road construction sector is a specific part of the construction industry. It happens very rarely that a section of a road is financed also by a private entity. The other [...]
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Freeze-Thaw Deicing salt Attack on Concrete: Towards Engineering Modelling
C. Thiel, V. Lomakovych, C. Gehlen

DBMC (2020).

Abstract
In order to reduce carbon dioxide emissions, the construction sector is increasingly using clinker-reduced concretes. Concrete with high amounts of ground granulated blast furnace slag (GGBFS) show increased durability performance in certain environmental conditions compared to concrete with Ordinary Portland cement (OPC). However, in laboratory studies, concrete with GGBFS show an increased initial scaling rate in comparison with OPC concrete. Changing weather conditions and high relative humidities > 70 % in field lead to less carbonation and thus, to a better freeze-thaw deicing salt resistance (FTDSR). Therefore, the current lab performance test penalizes GGBFS concrete. This contribution studied the impact of carbonation and intermittent dry periods on FTDSR of GGBFS concrete compared to that of OPC concrete. It could be shown that for concrete with OPC, intermittent dry periods lead to an accumulation of salt in the near surface, which causes a reduction of the scaling. GGBFS concrete, on the other hand, shows an opposite behavior: carbonation causes an increase in scaling after the dry period. GGBFS concrete samples with CO2-free pre-storage show the lowest scaling of all samples investigated. A better simulation of the behavior of GGBFS concrete could lead to economical as well as optimized solutions for the local environment conditions and enable the large-scale use of more environmentally-friendly concretes. Therefore, by taking the effect of carbonation and intermittent dry periods into account in a simple engineering model, the prediction of concrete scaling under consideration of real climatic conditions is possible in an eco-efficient manner.
Abstract
In order to reduce carbon dioxide emissions, the construction sector is increasingly using clinker-reduced concretes. Concrete with high amounts of ground granulated blast [...]
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Durability Studies of Self-Compacting Concrete containing Electric ArcFurnace Slag Aggregate
A. Santamaria, M. Skaf, V. Lopez, E. Briz, J. José, J. González

DBMC (2020).

Abstract
The structure of self-compacting concretes containing electric arc-furnace slag, their mechanical behavior, and their durability are all studied in an extensive experimental campaign, to evaluate the suitability of three concrete mixes for use in real construction works. Specimens manufactured with self-compacting electric arc-furnace slag concrete are subjected to wetting-drying and freezing-thawing test procedures, for their study in aggressive environments, especially marine environments. In general, all the test results were quite encouraging. It was once again demonstrated that the use of electric arc-furnace slag in concrete represents an opportunity to reduce both the volume of siderurgical waste generated in our society, and the consumption of fresh raw materials.
Abstract
The structure of self-compacting concretes containing electric arc-furnace slag, their mechanical behavior, and their durability are all studied in an extensive experimental [...]
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OSB and Marine Plywood: Performance Comparison for use with Light Steel Frame Walls in Brazil
M. Junginger, M. Resende, L. Oliveira, V. John

DBMC (2020).

Abstract
The use of light steel frame and wood frame in Brazil is still recent, hence there is little information about the durability of these technologies applied in Brazilian climate conditions. The wood-based boards are used as a part of the light steel or wood frame walls and are designed to contribute to the wall structural behavior (horizontal reinforcement and resistance to suspended loads). Once the information if such boards meet the DL (design life) set in the Brazilian code of residential building performance is still unknown, this paper analyses the technical characteristics of two woodbased boards - OSB and marine plywood - aiming to gather more information concerning durability under liquid water action. Thus, tests were carried out on samples of these two boards to evaluate their behavior against liquid water and after accelerated ageing test. In all cases, OSB showed to be more sensitive to early degradation than plywood.
Abstract
The use of light steel frame and wood frame in Brazil is still recent, hence there is little information about the durability of these technologies applied in Brazilian climate [...]
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Uncertainty and Sensitivity Analyses for Evaluating the Building Element‘s Replacement in Building LCA
K. Goulouti, P. Padey, A. Galimshina, G. Habert, S. Lasvaux

DBMC (2020).

Abstract
This paper presents a systematic way to consider the uncertainties of the building elements‘service lives within a stochastic framework, by defining the corresponding probability density functions, based on a service life database. This methodology is appropriate for screening and detailed building LCA, since the service life database offers the possibility to define the probability density functions of the service lives, in different level of details
Abstract
This paper presents a systematic way to consider the uncertainties of the building elements‘service lives within a stochastic framework, by defining the corresponding probability [...]
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Composite Façade Elements with Self-Cleaning Surface made of UltraHigh-Performance Concrete (UHPC)
J. Werder, P. Fontana, J. Hoppe, S. Bilgin, B. Meng

DBMC (2020).

Abstract
In the framework of the European project H-House various concrete façade elements were developed with the aim to ensure a long service life by combining a very durable material with selfcleaning properties. The façade elements presented are made of a shell of UHPC filled with blocks of aerated autoclaved concrete as insulating material. Self-cleaning properties were realized amongst others by imprinting a microstructure into the surface during casting. The paper focuses on selected technological aspects of the manufacturing process of prototypes which had to be performed in two concreting sections. Furthermore the challenges faced when upscaling the self-cleaning properties are addressed and the strategy to assess the self-cleaning properties by measuring the contact and the rolloff angel is presented. The results show that a successfull upscalaing process requires detailed planning and that the best results can often be achieved with a moderate work effort or material use.
Abstract
In the framework of the European project H-House various concrete façade elements were developed with the aim to ensure a long service life by combining a very durable [...]
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Macrocell Processes in Reinforced Concrete Structures
J. Lliso-Ferrando, J. Zamora, R. Bataller, J. Soto

DBMC (2020).

Abstract
Corrosion of steel embedded in reinforced concrete is the phenomena that most affects the durability of this type of structures. The control and analysis of the rebars can help detect this problem beforehand, contributing to prevent costly repairs made when the damage is quite advanced. Currently, there are several techniques for measuring the corrosion rate of steel, but they have the disadvantage of being slow or requiring specialized tools. In addition, these techniques need direct connection to the rebars, so removing the concrete cover layer is necessary. This destructive technique is sometimes impossible to do because there are analysis zones which are inaccessible due to they are buried or submerged. Recently, using sensors embedded previously casting and external electrical connections let analyse the corrosion without using invasive techniques. This study presents the complementary technique of analysing macrocell currents in order to know the origin and direction of current in reinforcements. This technique requires less time and non-advanced material, only an ammeter and electrical connection to the rebars, executed before casting. In addition, this parameter provides information about the real corrosion of the different parts of the structure. In this study it is performed the laboratory analysis of this technique by the use of specimens containing one anode and one cathode inside them creating a macrocell. The influence of different environments on macrocell current intensities shall be studied and compared with other studied parameters as corrosion density.
Abstract
Corrosion of steel embedded in reinforced concrete is the phenomena that most affects the durability of this type of structures. The control and analysis of the rebars can [...]
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Evaluation of Pore Structure of Hardened Cement Paste Immersed in Sodium Sulfate Solution
H. Sakata, K. Sato, S. Saito

DBMC (2020).

Abstract
The purpose of the present study is to evaluate pore structure of hardened cement paste immersed in sodium sulfate solutions and to experimentally examine the relation between the change of pore structure and hydration products. Cement paste specimens were immersed in sodium sulfate solutions and ion-exchanged water for two weeks. Since oxygen gas can pass through the pores having micro scale, it is possible to evaluate the effect of the pore structure on the oxygen transport in cement pastes. Thus, the oxygen diffusion coefficient (DO2) of the specimens after immersion were measured, and the pore volume and the pore size distribution were also measured. In addition, the phase compositions of the specimens were acquired. As a result, DO2 of the specimens immersed in the sodium sulfate solutions decreased as compared to the specimens immersed in the ion-exchanged water. The tortuosity of the specimens immersed in the sodium sulfate solutions increased due to decreasing of the pore volume having a diameter larger than 20 nm. There was a correlation between the volume of ettringite and the pore volume having a diameter larger than 20 nm. According to the above results, it was considered that the decreasing of DO2 in the case of sulfate immersion can occur as a result of the complication of the pore structure owing to filling of the pores by ettringite
Abstract
The purpose of the present study is to evaluate pore structure of hardened cement paste immersed in sodium sulfate solutions and to experimentally examine the relation between [...]
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Development of an Apparatus for Measuring the Load Acting on Joint Sealant when Movement Occurs
S. Ishihara, H. Miyauchi, A. Ito, K. Tanaka

DBMC (2020).

Abstract
The sealant that fills the joints of an exterior walls of building is subjected to weather loads, such as sunlight, ambient temperature, and rain, as well as a movement of the joints. As a result, the sealant gradually deteriorates under the combined deterioration factors of weathering and movement. Meanwhile, the results of a 15-year outdoor dynamic exposure test conducted in Japan using the methodology of ISO 11617 showed that the progress of damage varies greatly depending on the type of sealant and the stress relaxation rate. However, the mechanism of damage progression is unclear. In the present study, we focused on the load when the sealant moves and developed a load-measuring apparatus as the first step in clarifying the relationship between the progress of damage and the load. The load was measured at −20, 23, and 40 °C for test specimens with different stress relaxation rates, and it was confirmed that the developed load-measuring apparatus was able to measure the load correctly. Furthermore, it was shown that it is difficult for the stress of the sealant with a high stress relaxation rate to relax over time at low temperature but easy at high temperature, and the load increases when switching from the compressed state to the extended state.
Abstract
The sealant that fills the joints of an exterior walls of building is subjected to weather loads, such as sunlight, ambient temperature, and rain, as well as a movement of [...]
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Durability of FRP Immersed in Water. Changes in Mechanical Properties
E. Bernat-Maso, M. Lis, L. Mercedes, L. Gil

DBMC (2020).

Abstract
Fibre Reinforced Polymers (FRP) have been widely used to strengthened construction structural elements in the last years because of their mechanical pros. However, the durability of these materials is always controversial. In particular, the effect of long-term contact with water on the mechanical properties of FRPs is studied in this research throughout the implementation of accelerated degradation tests. Samples of Carbon FRP and Glass FRP were immersed into supply water, water with salts and surfactants and highly chlorinated water. In all cases, electrical current passing through the samples was also imposed. Tensile tests on pristine and degraded samples were carried out to determine the influence of these aggressive environments on the tensile strength and the Young‘s modulus of the specimens. Finally, superficial (ATR) FT-IR analyses were conducted to assess possible chemical changes in the samples surfaces. Results indicated that the chemical composition of used resins was not modified due to the water exposure. No hydrolysis process took place during testing time on the surface. However, mechanical properties were reduced, especially when samples were exposed to plain supply water, which may be related to the physical degradation caused by moisture intake by diffusion.
Abstract
Fibre Reinforced Polymers (FRP) have been widely used to strengthened construction structural elements in the last years because of their mechanical pros. However, the durability [...]
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Risk-Based Approach for Improving Concrete Bridges‘ Inspection Planning
S. Tronsli, S. Samarakoon, R. Ratnayake

DBMC (2020).

Abstract
Visual inspection forms the basis of the inspection planning process for concrete bridges. The authority responsible for bridge inspection maintains a database to record past inspection results, in order to plan future inspections. It is a challenge to recognize and classify bridges that it is essential to inspect based on inherent requirements. This is further exacerbated by the limited budget available. This manuscript describes a methodology for classifying bridges based on risk of potential failure and distributing the annual inspection budget for carrying out inspections on bridges accordingly. The absence of such a methodology allocation of resources for bridge inspection without real need. For example, on some occasions it is not necessary to inspect certain bridges on a time basis. Hence, this study focuses on developing an inspection-planning approach based on the actual and predicted condition (i.e. based on the database of past inspection data). It enables the bridges to be classified into different categories, based on the risk of potential failures. This enables the effective distribution of annual budgets among the bridges, avoiding unnecessary inspection that incurs pointless inspection costs.
Abstract
Visual inspection forms the basis of the inspection planning process for concrete bridges. The authority responsible for bridge inspection maintains a database to record past [...]
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Earth Construction Durability: In-Service Deterioration of Compressed and Stabilized Earth Block (CSEB) Housing in Algeria
A. Brara, A. Benidir, M. Mahdad

DBMC (2020).

Abstract
The present work deals with a unique in-service valuation of CSEB structures in Algeria. The inspection tries to bring out the impact of long time exposure under different and opposite climate and micro-seismic contexts. The diagnosis methodology is inspired by the approach largely adopted for the rehabilitation of traditional architecture. It involves the compilation of the previous survey reports, visual inspection of the structures, in-situ and laboratory tests to assess the residual CSEB mechanical properties. The CSEB constructions are located in the coastal north and the desertical south part of Algeria and were exposed respectively to a long-term Mediterranean and Saharian climate. The results of the investigation show that the CSEB in the construction located in the northern region is increasingly altered by the humidity. As the relative humidity rises, the fouling layers grow over some level. The surface pitting which is the consequence of long exposure to the wetting/drying cycles is also observed. The outer surfaces of the walls were honeycombed which reduce drastically the block resistance against the abrasion test. In some cases, differential erosion appears in the front of the walls, which indicates that the alteration does not proceed at the same rate from one area of the block to the other. However, owing to highly cementitious mortar used to join the earth blocks, the edges and corners remain unchipped. In the southern region where the arid climate dominating, the degradation of the CSEB is less prone to water attack but roughly exposed to the effect of the winddust frequent in this region and to the unawareness of the population. The paper presents also some recommendations to improve the earth construction durability with CSEB technique.
Abstract
The present work deals with a unique in-service valuation of CSEB structures in Algeria. The inspection tries to bring out the impact of long time exposure under different [...]
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A New Alkali-Silica Reaction (ASR) Mitigation Technology - Part I: Comparing with Li, Ca, Al Salts, and Densified Silica Fume
T. Vickers, M. Myers, J. Atienza, L. Ko, P. Seiler, F. Ong

DBMC (2020).

Abstract
Alkali-silica reaction (ASR) is a major concrete durability problem. The occurrence of ASR results in significant maintenance and reconstruction costs to concrete infrastructures all over the world. Ever since Stanton (1940) discovered the expansive characteristics of ASR in 1940, there has been much speculation as to the cause and actual mechanism of expansion. Current market solutions are not always sustainable, such as hauling non-reactive aggregates or fly ash from long distance; or use of Li-based chemical admixture that is facing challenge of raw material‘s availability. The current article will present a patent pending technology which provides a commercial solution for mitigating the ASR. The ASR mitigating effect of this technology is compared with lithium, calcium, and aluminum salts, and densified silica fume.
Abstract
Alkali-silica reaction (ASR) is a major concrete durability problem. The occurrence of ASR results in significant maintenance and reconstruction costs to concrete infrastructures [...]
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Thermodynamic Processes in Nanostructured Thermocoatings
D. Bozsaky

DBMC (2020).

Abstract
In the 21st century, global climate change and the high level of fossil energy consumption have introduced changes affecting all sectors of the economy, including the building industry. This process has prompted EU members to create strict regulations in building energetics. It has become a serious task for architects to find more effective ways for thermal insulation. One of these options is the application of nanostructured materials. Among them nano-ceramic thermocoatings open a wide range of research fields, because complete agreement had not been already found about their insulating effect. In order to explore and describe the thermodynamic process inside nano-ceramic thermocoatings 6 series of heat transfer resistance experiments were performed in 2014-2018. Several building structure configurations with 12 different orders of layers were tested with a standard heat flow meter. On basis of these results it could be concluded that in case of nano-structured thermocoatings convective heat transfer coefficient might be taken account in different way than in case of traditional macro-structured thermal insulation materials. Based on research results, the limits of its applicability can also be concluded. It has also been found that the insulating effect of nanostructured thermocoatings depends on the material characteristics of the insulated surface.
Abstract
In the 21st century, global climate change and the high level of fossil energy consumption have introduced changes affecting all sectors of the economy, including the building [...]
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Probabilistic Approach to the Service Life Prediction of Timber Claddings
A. Silva, A. Prieto

DBMC (2020).

Abstract
The service life of buildings and components is extremely difficult to model and predict, mainly due to the uncertainty and variability associated with the degradation phenomena. These uncertainties are usually related with the intrinsic randomness of natural phenomena, such as the environmental degradation agents. In order to deal with these uncertainties, in this study, a stochastic approach is used, to model the service life of timber claddings. For this purpose, a logistic regression analysis is used to evaluate the probability of timber claddings to reach the end of their service life over time. Moreover, the impact of the environmental exposure conditions (e.g. facades orientation, distance from the ocean, exposure to damp and exposure to wind/rain action), which influence the degradation and service life of timber claddings, is also evaluated. The proposed models are applied to 150 timber claddings, located in Valdivia (South Chile), which have been analysed during an extensive fieldwork survey. The results obtained in this study aid the definition of maintenance plans, in a technically informed manner, in order to promote the conservation of these claddings, which are an important symbol of the local identity of this region, depicting a complexity of cultural values, inherited by Spanish and German colonisations.
Abstract
The service life of buildings and components is extremely difficult to model and predict, mainly due to the uncertainty and variability associated with the degradation phenomena. [...]
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Maintenance-Oriented Design in Architecture. A Decision Support System for the Evaluation of Maintenance Scenarios Through Bayesian Networks Use. A Case Study: the Headquarters of ING Groupe in Amsterdam
M. Sivo, D. Ladiana, F. Novi, C. Salvatori

International Conference on Durability of Building Materials and Components

Abstract
This study was developed at the Department of Architecture of Pescara and Department of Energy, Systems, Territory and Construction Engineering of the University of Pisa as part of an experimental thesis that led to the implementation of a Decision Support System. The objective of the work was to implement a tool capable of evaluating - in relation to the choices concerning the morphology of the building, the construction technologies, the materials and the design of the architectural elements - the levels of maintenance quality implemented in the various phases of the project, from the first phases, in which few relevant decisions are made, to the executive phase characterized by a multiplicity of choices. The aim was to construct a tool in which the reliability of the evaluations was related to the quantity and quality of the data that feeds the decision-making process, but which is also able to evaluate preliminary decisions based on the elements of choice that characterize the first phases of the project. The conceptual model has been defined through the construction and implementation of a Bayesian Network or a graphical system of probabilistic inference able to represent the set of stochastic variables and their conditional dependencies through the use of a direct acyclic graph. Through the interrogation of the network it is therefore possible to evaluate through the expression of a synthetic index, a real overall rating of the different aspects that contribute to define the maintenance quality. The use of Bayesian Networks, in the light of the analyses carried out on an experimental basis - exemplified here on the case study of ING Groupe headquarters - for the ability to control a multitude of factors linked to the durability of materials, the morphology of systems and ease of intervention, seems capable of generating useful, effective and expandable tools to support the design decision-making process.
Abstract
This study was developed at the Department of Architecture of Pescara and Department of Energy, Systems, Territory and Construction Engineering of the University of Pisa as [...]
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Smalti Murano Glass Tessella’s Applied Outdoor in the Trencadís Catalan Modernism Mosaic: Recognition of Preliminary Alteration Patterns
R. Fabregà, J. Mestre, P. Arias

DBMC (2020).

Abstract
This contribution presents previous results of a study carried out with the aim of achieving better results in the restoration processes by replacing the tiles of an exterior mosaic tiling of the Trencadís type of Catalan Modernism. In this case the trencadís tiles come from the cutting of pieces, called piastras, of opaque and mass-colored glass called Smalti Murano glass. These companies have extensive color catalogs that, although not exactly the same as they were a century ago, are close enough for these replacement tasks. Each color corresponds, however, to a different composition of glass and a slightly different manufacturing process. These differences favor that the differences of color always go accompanied also of differences of superficial aspect. However, not all color references currently available have the same surface quality since this product, during its manufacture, acquires primary defects typical of artisanal processes. So far the predominant criteria for the selection of the new references of piastras that must replace the product damaged by the extensive exposure to the weather as a coating are based primarily on color. However, durability requirements must also be part of the selection criteria for substitution references. The primary defects that a product already presents in its superficial quality are often indicators of either a more irregular quality or of circumstances that favor the early appearance of secondary defects throughout its useful life. The main objective of this study is to ensure, in restoration work by substitution, the selection of the best piastras from the point of view of surface quality, to apply on site the most similar tiles of tone and with greater durability. This study is part of a collaboration between the study group LiTA (Laboratori d‘Innovació i Tecnologia de l‘Arquitectura) (UPC) and a private non-profit organization.
Abstract
This contribution presents previous results of a study carried out with the aim of achieving better results in the restoration processes by replacing the tiles of an exterior [...]
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Post Peak Behavior of Carbonated Concrete Structure - A Case Study of the Former Shime Mining Office Vertical Derrick in Japan
K. Su, K. Imamoto, T. Noguchi, M. Kanematsu, H. Hamasaki, K. Teranishi, C. Kiyohara, M. Yamada

DBMC (2020).

Abstract
This paper is a report on the investigation results of the Former Shime Mining Office Vertical Derrick, which was built in 1943 and was 75 years old at the time of the investigation. The building suffered from serious deterioration including rebar corrosion, which led to large area of concrete spalling. In this report, aggregation data of concrete spalling has been presented along with the investigation results of cover thickness. According to the investigation results, concrete spalling occurred in places where cover thickness was less than 25 mm. And According to the aggregation data, concrete spalling flakes increased by approximately 200 pieces per year, with the average size of 10 cm in diameter. Also, a possible relation between concrete spalling and rainfall was observed during the investigation. Equations using the proportion of wet area affected by rainfall to estimate the area of spalling are proposed, although the value of empirical coefficientαneeds further discussion, including collecting data from other buildings where spalling occurs.
Abstract
This paper is a report on the investigation results of the Former Shime Mining Office Vertical Derrick, which was built in 1943 and was 75 years old at the time of the investigation. [...]
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Determination of the Deterioration Characteristics of Facade Materials: A Case Study
N. Kokulu

DBMC (2020).

Abstract
Deterioration of the facade materials of a building and its importance are topics that are not getting the attention that they deserve and need. If a material can’t meet its accepted performance criterion during its service life then deterioration may occur on the surface, inside, under or at the structure of the material. Environmental, construction related, and human related agents collaborate with the mechanisms and make an effect which concerns the durability. Therefore, detecting the deteriorations of the materials play an important role for the maintenance planning. This study aims to detect the agents, mechanisms and effects of the deteriorations of a case building. A systematic approach was developed by making literature review. Hostile environmental analysis and building facade inspection have been made by the visual observations on a specific day. Deteriorations occurred at granite, wood composite, aluminum, glass and ceramic materials have been discussed.
Abstract
Deterioration of the facade materials of a building and its importance are topics that are not getting the attention that they deserve and need. If a material can’t meet [...]
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Case Study of Pathological Manifestations of Neoprene Support Devices in Infrastructure
F. Gonçalves, L. Alves, A. Haddad, E. Vazquez

DBMC (2020).

Abstract
The so-called works of special arts, are constructions of high complexities that allow the advancement of widening gaps and overcoming obstacles previously unthinkable. With the increase in magnitude of these structures, in addition to greater investments, the maintenance of these structures becomes an increasingly important factor for engineering. Among the elements of bridge structures, the support devices are components with important structural functions, being essential for their proper functioning and especially the durability of the entire structure. This paper aims to evaluate the pathological manifestations in support devices so, according to inspections performed and the diagnosis of causes, define their best practices and treatments for the maintenance and mitigation of the pathologies found. In the practical study the following steps were performed: survey and selection of the structures currently under maintenance of MetrôRio; selection of criteria for the evaluation of pathologies; carrying out inspections; comparative analysis between the viaducts to determine the priority order for negotiations; and definition of conduct. The results obtained were the result of evaluation of the field analysis, diagnosis and comparison with tests performed in support devices. Having as input the tests in the support devices, the best treatments and suggestions to avoid new pathologies were proposed.
Abstract
The so-called works of special arts, are constructions of high complexities that allow the advancement of widening gaps and overcoming obstacles previously unthinkable. With [...]
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Deformation Velocity Survey in Mortar and Cement Paste Specimens Subjected to External Aggressive Attacks
C. Tedeschi, E. Garavaglia

DBMC (2020).

Abstract
The durability of concrete depends not only on the composition of the material and its resulting porosity, but also on the environmental conditions. Contact between concrete or cement mortars with water and soils containing sulphates, of a natural, biological origin or deriving from pollution, can activate chemical reactions in the cement paste inducing an expansion and degradation of the concrete. To evaluate the behaviour of the cementitious material subjected to various external aggressive attacks, prismatic samples of cement paste and mortar samples produced with the same binder (Portland cement) were immersed in demineralised water and in various solutions containing 5% and 10% sodium sulphates. Their expansion was monitored over time by a direct length measurement. This paper shows the results achieved in a rather long laboratory investigation and a first hypothesis has been formulated on the possible expansion rate in the first 56 test days and in the following 850 days.
Abstract
The durability of concrete depends not only on the composition of the material and its resulting porosity, but also on the environmental conditions. Contact between concrete [...]
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Innovative Approaches to Increase Service Life of Poplar Lightweight Hardwood Construction Products
J. Acker, X. Jiang, J. Bulcke

DBMC (2020).

Abstract
During the second half of last century the forestry-wood chain has evolved and today ecosystem services in a sustainability framework are important. Forests are intended to provide services for the bio-economy, human health, biodiversity and climate control. An increased need for more renewable resources both for material and energy use has initiated extra interest for the potential to produce more lignocellulosic biomass, in short to increase wood production. One option is to provide in complementary production in planted forests. Both forestry and agriculture can take part in this. The cultivation of poplar hybrids in the temperate regions is a key option for the current and future bioeconomy. These fast-growing trees are producing lightweight hardwood with a low natural durability, but with an important potential as construction material especially as engineered wood products. All wood protection methods are of interest to be evaluated for this wood resource, making it suitable even for high quality applications. Poplar, for many reasons, has been nominated as hardwood with the best potential to perform similarly as softwoods for applications in wood construction. Benchmarking with wood species like spruce is relevant for several engineered wood products like plywood, LVL and even CLT. Wood treatments to increase durability have evolved from traditional wood preservation towards modification techniques such as thermally modified timber. Innovative poplar based products have been assessed on their performance and are designed to fit for purpose in relation to a specific combination of use class and service life. Introducing innovative poplar based construction product for green building requires adequate testing tools. Performance based assessment should allow to integrate different protective measures. Related to moisture dynamics and the linked fungal decay risk, opportunities to extend service life are manifold. Treatment can be differentiated e.g. for cladding (building envelope) and loadbearing construction components. Simple or sophisticated modification processes can alter the equilibrium moisture content. The use of wood based panels and new engineered wood products allow for better moisture control impacting fungal decay risk, but also alter the probability of insect damage. This paper intends to present several innovative poplar based construction products and show some cases of benchmarking in relation to an integrated service life approach.
Abstract
During the second half of last century the forestry-wood chain has evolved and today ecosystem services in a sustainability framework are important. Forests are intended to [...]
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Effect of Mortar Age on the Textile-to-Mortar Bond Behavior
A. Dalalbashi, B. Ghiassi, D. Oliveira

DBMC (2020).

Abstract
Textile-reinforced mortar (TRM) composites have received extensive attention as a sustainable solution for seismic strengthening of masonry and historical structures. This new system is composed of textile fibers embedded in an inorganic matrix and is applied on the masonry and the concrete substrate surface as an externally bonded reinforcement (EBR) system. The bond at the textile-to-mortar interfaces is the main stress-transfer mechanism and, therefore, should be thoroughly investigated. Furthermore, the effectiveness of TRMs in improving the seismic performance of existing structures is highly dependent on the durability of its components, materials, textile-to-mortar bond, and their long-term behavior. Due to the novelty of these materials in application to masonry structures, several aspects related to the durability and long-term performance of them are still not clear. To that end, a new study has been launched that looks at the time effect on the mechanical properties and bond behavior between fiber and mortar. For this purpose, two different hydraulic lime-based mortars, as well as steel and glass fibers, are used to investigate the effect of mortar age on the TRM system after 180 days. The results show that at the early age of mortars, their mechanical properties, and the bond behavior of textile-to-mortar have been increased. Another critical point to remember is that by increasing the mortar age, textile-to-mortar bond and mortar strength are decreased.
Abstract
Textile-reinforced mortar (TRM) composites have received extensive attention as a sustainable solution for seismic strengthening of masonry and historical structures. This [...]
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Development of a Damage Detecting Method for RC Slabs by Means of Machine Learning
Y. Tanaka, T. Nishida

DBMC (2020).

Abstract
It is beneficial to understand damage conditions of RC structural members by non-destructive methods. In this study, K-means clustering method was applied to the AE wave data in order to develop a damage detection method. From the result of this study, the damaged area had the relatively large number of AE hits and AE energy. In addition, from the result of the K-means clustering of the power spectral density of AE waves, the data could be separated into the obviously damaged area and other areas.
Abstract
It is beneficial to understand damage conditions of RC structural members by non-destructive methods. In this study, K-means clustering method was applied to the AE wave data [...]
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A Maintenance Management Model. Upgrading and Experimentation
M. Lauria, M. Azzalin

DBMC (2020).

Abstract
The paper deals with the first results of the activities of BIG Building Innovative Governance srl, Academic Spin-Off and Innovative Start Up, which provides smart services for Building Maintenance and Facility Management also launching circular R&D actions in the relative reference areas. The contribution introduces some actions actually in progress geared to upgrading the Maintenance Management Model, M3, specifically aimed at managing the life cycle of buildings. The current stage of development corresponds to a TRL 4. TRL 8 is that expected by the end of 2020. Characterized by interconnectivity and scalability, the Maintenance Management Model is a dynamic, collaborative and implementable system, whose architecture consists of three separated but strongly interconnected devices: an information interface system, a collaborative platform, a remote cloud. An ICT network infrastructure able to activate using BIM models (IFC and COBie standards) circular information workflows between all operators and/or users involved in Maintenance and Facility Management processes. It allows the development and/or implementation of information management and sharing models based on Open Data and Semantic Web. Its use will also promote shared lexicons and the circulation of knowledge within a holistic process of managing information from and for Maintenance. The use of BIM models and the possibility of collecting and managing a large amount of data will be oriented to the structuring of information feedback databases according to ISO 15686 guidelines. In this way, available information can be usefully transferred in life cycle assessments and service life prediction of materials and components.
Abstract
The paper deals with the first results of the activities of BIG Building Innovative Governance srl, Academic Spin-Off and Innovative Start Up, which provides smart services [...]
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Mechanical Behaviour of ETICS in Presence of Water
F. Cecconi, G. Cocchetti, A. Cornaggia, T. Villa

DBMC (2020).

Abstract
Climate change and the request for better assets’ energy performances are forcing the construction sector towards passive or even active buildings: assets with a positive balance between energy production and consumption. Building insulations play a crucial role in reducing energy demand. One of the most used technology to insulate new and refurbished buildings are the External Thermal Insulation Composite Systems (ETICS). Despite their thermal advantages, low cost, and ease of application, these systems may have serious problems if not well designed. Cracks on the coating layer are among the most common pathologies during ETICS service life. They have been studied using a Finite Element Method (FEM) analysis on two different types of ETICS in order to understand how cracks and the mechanical characteristics of materials used in the ETICS are related. The results show that errors during ETICS installation impacts on cracks occurrence as much as the mechanical performances of some layers. The FEM analysis have been complemented by the experimental study of the mechanical behavior of the coating layer under the effect of rainwater, in order to better understand ETICS behavior over their service life.
Abstract
Climate change and the request for better assets’ energy performances are forcing the construction sector towards passive or even active buildings: assets with a positive [...]
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Performance of European Wood Species in Above Ground Situations After 10 Years of Weathering: Evidence of a Positive Impact of Proper Design
M. Kutnik, M. Montibus, M. Gabillé

DBMC (2020).

Abstract
. Most of European native wood species used outdoors are expected to last less than 10 years if left untreated and exposed to severe environmental conditions such as high humidity and biological agents. However, the current classification of wood’s natural durability based on EN standards does not fully reflect real end-use conditions, often underestimating wood’s performance in use. In addition, the importance of design details and the role they play in enhancing service life, especially in the case of outdoor applications, is often neglected. With the aim of evaluating the positive impact of proper design on wood’s service life, large-scale experimental devices, manufactured according to different designs (water draining / trapping) from six native wood species, were installed in 2009 in two French cities benefiting from different climatic conditions (oceanic / continental). The results of the evaluation carried out after 10 years of natural weathering demonstrated that (1) significant differences in the ability to withstand decay over time exist depending on the selected design details and the climatic conditions encountered in the experimental fields; (2) high variability in the resistance of non-durable spruce and poplar wood against fungal decay was noticed for each tested design, but with an unexpected high percentage of elements performing very well; (3) the moderately durable heartwood of larch, maritime pine and Douglas fir was mostly unaffected by decay even under severe conditions of exposure to rain (decking modules), suggesting these species may have greater value for outdoor applications without any preservative biocidal treatment than previously assumed.
Abstract
. Most of European native wood species used outdoors are expected to last less than 10 years if left untreated and exposed to severe environmental conditions such as high [...]
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Non-Destructive Evaluation of Micro-Cracked SCC by Ultrasonic Waves
I. Palomar, G. Barluenga, H. Varela, J. Puentes, Á. Rodríguez

DBMC (2020).

Abstract
Self-Compacting Concrete (SCC) is an effective, reliable and safer technology to cast-inplace concrete structures. However, the large amount of paste required to achieve its high flowability may increase drying shrinkage at early age, due to the undesirable effects of curing conditions, producing micro-cracking and damaging concrete members. When this happens, an evaluation of the hardened SCC is necessary and Non-destructive testing techniques (NDT) can be suitable. Among NDT, Ultrasonic pulses (US) have showed to be very useful due to its portability, easiness of application and sensitivity to changes in material microstructure, porosity and presence of defects. In order to evaluate the applicability of ultrasonic (US) waves to better understand the relations among composition, microstructure, properties, curing conditions and micro-cracking, an experimental program using transmission P- and S- waves was carried out on SCC with limestone filler (LF), microsilica (MS) and nanosilica (NS), set and hardened under different curing conditions: 10, 20 and 30 °C and 40 and 80% relative humidity. Free shrinkage and double displacement restrained slabs were tested and cracking potential due to Early Age Shrinkage was assessed. Ultrasonic transmission time and wave amplitude of the raw US signal were measured and Ultrasonic pulse velocity (UPV) and attenuation coefficient were calculated. In addition, some physical and mechanical properties of cracked and un-cracked samples were measured. The aim of this study was to compare US parameters to hardened properties of cracked and un-cracked SCC. Correlations for SCC micro-cracking based on US parameters were identified, demonstrating the potential of using transmission US P- and S- waves as an evaluation technique for micro-damaged SCC
Abstract
Self-Compacting Concrete (SCC) is an effective, reliable and safer technology to cast-inplace concrete structures. However, the large amount of paste required to achieve its [...]
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Influence of Drying on Accelerated Carbonation Testing of Concrete
J. Gallias, B. Fiorio, Y. Tong, M. Benaissa

DBMC (2020).

Abstract
The aim of this work is to better understand the influence of drying conditions and moisture content of concrete on the carbonation kinetics during accelerated tests. Cylindrical specimens of a typical concrete formulation for buildings were dried, after 28 days wet curing, under three different conditions: 80°C, 45°C and 20°C and 50% RH. The carbonation depth and the height of water absorption were measured during 70 days testing under 3% CO2, 20°C and 65% RH. The results show that there is a significant difference in the drying behavior of cylindrical specimens between the lateral cast surface and their circular free surface. But, the drying cycle before accelerated carbonation tests has more influence on the carbonation rate than the type of exposed surface
Abstract
The aim of this work is to better understand the influence of drying conditions and moisture content of concrete on the carbonation kinetics during accelerated tests. Cylindrical [...]
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Effect of Internal Hydrophobization on the Properties of Porous, Cementitious Materials
K. Grabowska, M. Koniorczyk

DBMC (2020).

Abstract
Water is one of the main factors affecting the durability of porous materials and it is one of the most common causes of their degradation. Physical phenomena such as freezing or salt crystallization, as well as the development of fungi and moulds, are caused by the presence of moisture. In wet material thermal conductivity coefficient increases and the heat loss begins to rise. Hydrophobization is one of the protecting methods of porous materials against water. Two different type of water-repellent agents were used for the internal hydrophobization. The first of them is an aqueous emulsion of silane: triethoxy(octyl)silane (OTES) and the second one is also an aqueous emulsion but the matrix is poly(dimethylsiloxane) (PDMS). The paper focuses on the use of organosilicon water repellents. The main purpose of this paper is to determinate the possibility of use organosilicon agents as admixtures to internal hydrophobization. We compared results obtained for two different silicon-based admixtures. We investigated influence of both water-repellents on basic characteristics such as: absorbability, capillary water absorption and mechanical properties of cement mortar as well as heat of hydration of cement paste.
Abstract
Water is one of the main factors affecting the durability of porous materials and it is one of the most common causes of their degradation. Physical phenomena such as freezing [...]
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Hygrothermal Performance Difference of Wooden Beam Embedded in an Internally Insulated Masonry Wall in 2D and 3D Models
X. Zhou, J. Carmeliet, D. Derome

DBMC (2020).

Abstract
Internal insulation of masonry walls may significantly increase the decay risk of embedded wooden beams due to lower temperature and consequently lower drying potential in the existing wall. Since high moisture contents will affect the performance and service life of wood, the study of moisture-related damage problems in wooden beam-ends in internally insulated masonry walls is of great importance. In the previous studies, the numerical study of hygrothermal performance of wooden beam-ends is performed only with 2D models. In this paper, we study whether a 2D numerical model can represent accurately the 3D hygrothermal behavior of wooden beam-ends. Therefore, the difference between 2D and 3D model results of the hygrothermal performance of wooden beam-ends embedded in an internally insulated masonry wall is analyzed. The difference of temperature and relative humidity in wooden beam-end between 2D and 3D models is in general small. However, 2D hygrothermal models show much lower relative humidities and thus lower moisture risk at some locations in the wooden beam-end. We find that a 3D hygrothermal model more accurately simulates the hygrothermal behavior.
Abstract
Internal insulation of masonry walls may significantly increase the decay risk of embedded wooden beams due to lower temperature and consequently lower drying potential in [...]
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Deterioration of CLT under Humid and Dry Cyclic Climate
S. Nakajima, Y. Sakabe, S. Kimoto, Y. Ohashi

DBMC (2020).

Abstract
Cross laminated timber (CLT) are composed of longitudinal layers and cross layers. And as the laminations of the adjoin layers are glued orthogonally deterioration of the laminations such as check and shake and delamination can be rather frequently come out when CLT is exposed to humid and dry cyclic climate. In Japan more than 100 CLT buildings have been constructed and the number of CLT building is increasing. In some buildings the CLT is designed as to be the exterior members and exposed to the outdoor climate. Several CLT buildings that have CLT as exterior members was investigated to make clear what was ongoing on the CLT panels exposed to outdoor climate. Remarkable check and shake, warp and delamination was observed for the CLT in some of the investigated buildings. To bring out the mechanism of the distortion of CLT under humid and dry cyclic climate and to give a solution to prevent deterioration of CLT a series of laboratory tests were conducted. The CLT panels were set in a climate chamber and exposed to a humid and dry cyclic climate. And the moisture content and the movement of the laminations of CLT were measured. The movement was affected by the species of the laminations and also by the direction of the surface, sap-side or heart-side. And the film forming type painting worked well as to prevent the deterioration and the penetrating type painting could slightly reduce the deterioration.
Abstract
Cross laminated timber (CLT) are composed of longitudinal layers and cross layers. And as the laminations of the adjoin layers are glued orthogonally deterioration of the [...]
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Monitoring the Early-Age Shrinkage Cracking of Concrete with Superabsorbent Polymers by Means of Optical Fiber (SOFO) Sensors
J. Filho, D. Snoeck, N. Belie

DBMC (2020).

Abstract
Concrete structures are subjected to shrinkage since the moment when the water makes contact with the cement. From that moment on, depending on the concrete composition and its curing conditions, chemical, autogenous and drying shrinkage might increase the risk of early-age cracking. Once a crack is formed, it may become the preferential path for the ingress of many aggressive agents inside the structure increasing the probability of damage due to corrosion, carbonation and other mechanisms. The use of superabsorbent polymers (SAPs) has been extensively studied to reduce the shrinkage cracking risk in mortar specimens by acting as internal curing agent to mitigate autogenous shrinkage. In this paper, a commercially available SAP was investigated as shrinkage reducing agent by means of internal curing in concrete specimens. The shrinkage of the concrete was monitored for 28 days with both a demountable mechanical strain gauge (DEMEC) and optical fiber sensors (SOFO). The SAP-containing concrete showed a complete mitigation of autogenous shrinkage during 28 days of measurement, for both methods. The SOFO sensors showed the occurrence of cracks after 7 days for the reference mixture, while for the SAP containing mixture, no crack was identified during the 28 days of measurements.
Abstract
Concrete structures are subjected to shrinkage since the moment when the water makes contact with the cement. From that moment on, depending on the concrete composition and [...]
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Behaviors of Concrete with Recycled Clay Brick as Fine Aggregate
W. Yang, X. Cai, D. Jiangjiu

DBMC (2020).

Abstract
Massive waste materials were produced by the construction and demolition industry every year. In residential constructions, clay bricks are a dominant material and they account for a large proportion of construction and demolition waste. Using crushed bricks in cement concrete is an effective way to preserve natural aggregate and to reduce construction and demolition waste. The mechanical properties, the permeability and the carbonation resistance of concrete with recycled clay brick as fine aggregate were studied in this paper. The results showed that the compressive strength, the flexural strength and the impermeability of concrete decreased with the increasing of the replacement percent of recycled clay brick. However, the permeability of concrete with the water to cement ratio of 0.35 was still at the “Low” level when the replacement percent was less than or equal to 75%. The carbonation resistance of concrete using recycled clay bricks as fine aggregate was degraded.
Abstract
Massive waste materials were produced by the construction and demolition industry every year. In residential constructions, clay bricks are a dominant material and they account [...]
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State of Maintenance in Relation to Property Regime, Tenancy and Uses of a Large Sample of Residential Buildings Located in the Most Vulnerable Areas of the City of Barcelona
S. Vima-Grau, C. Cornadó, P. Garcia-Almirall

DBMC (2020).

Abstract
In a context of downturn of public investment after the financial crisis of 2007, an increase of social and economic inequality takes place in territories and cities. Socio-residential vulnerability is intensified in certain urban areas where processes of socioeconomic and socio-spatial regression are related with the resident population difficulties to access resources for the intervention and maintenance of an aging residential building stock that gradually decays. Mediterranean cities in Southern Europe and precisely the city of Barcelona face the added difficulty of counting with a residential built stock of mostly private property, accounting many situations of horizontal property in which each building is managed by a community of owners who are not necessary householders and users. The present study consists of an analysis of the relation between the state of maintenance of residential buildings and the property regime, tenancy and uses, based on the observation of common spaces and elements of a large sample of buildings located in the most vulnerable areas of the city of Barcelona. The provided results can contribute to foster improvements in future public rehabilitation programs and policies. Particularly according to local challenges to guarantee and promote durability of a mostly privatelyowned residential built stock that is located in areas where socioeconomic difficulties hinder the residents’ capacity to carry out rehabilitation or maintenance actions. Management of the maintenance of the residential built stock must take into account the repercussion of particularities in property regimes, tenancy and uses, especially when it refers to common spaces and elements of residential buildings.
Abstract
In a context of downturn of public investment after the financial crisis of 2007, an increase of social and economic inequality takes place in territories and cities. Socio-residential [...]
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Durability Based Service Life Estimation for Chloride Exposed Cracked and Self-Healed Concrete
N. Belie, B. Belleghem, S. Keßler, P. Heede, K. Tittelboom

DBMC (2020).

Abstract
Chloride ingress in cracked concrete leads to rapid corrosion of embedded steel reinforcement and a decrease of the expected service life. Corrosion monitoring experiments showed that a 300 μm wide crack caused initiation of corrosion of a rebar (Ø 10 mm) with a concrete cover of 26 mm within three weeks of cyclic exposure to a 33 g/l NaCl solution. After a period of unstable corrosion activity during the first 20 weeks of exposure, corrosion propagated further at a relatively high rate (0.345 to 0.718 mm³/week). Application of a theoretical pitting model revealed that a reduction of about 50% of the rebar cross-section would occur after a period of 9 to 20 years of continuous cyclic exposure to chlorides. To avoid such rapid degradation, the use of self-healing concrete can be proposed. Introduction of macro-encapsulated polyurethane into the concrete matrix, will lead to the formation of a (partial) barrier against ingress of chlorides at the moment cracks appear. Corrosion monitoring experiments showed that the autonomous crack healing could not always prevent corrosion initiation, but caused an important reduction of the corrosion rate during the 44 weeks exposure period. The mean rate of volumetric loss of steel amounted to 0.042 mm³/week, about 15 times lower than for the untreated cracked samples. The rebars also showed no or very limited signs of corrosion after visual inspection. The simplified pitting model indicated that a 50% reduction in steel cross-section would take more than 5 times longer for samples with self-healing properties versus ordinary cracked samples.
Abstract
Chloride ingress in cracked concrete leads to rapid corrosion of embedded steel reinforcement and a decrease of the expected service life. Corrosion monitoring experiments [...]
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Development of 3D Printing Technology for Geopolymers
K. Korniejenko, M. Łach, J. Mikuła, M. Hebdowska-Krupa, D. Mierzwiński, S. Gądek, M. Hebda

DBMC (2020).

Abstract
The article presents the first results of the project under the title: ‘Development of 3D printing technology for construction and facade prefabricated elements made of concrete composites and geopolymers’, grant no. POIR.04.01.04-00-0096/18, funded by the National Centre for Research and Development in Poland, within the framework of programme: ‘Smart Growth Operational Programme 2014-2020, IV Increasing the research potential, 4.1.4: ‘Application projects’. The main aim of the project is design and development of the innovative large-format printer using geopolymers for 3D printing for residential houses. It allows the development of a technology for the production of a universal residential building, with a construction that is easy to transport and fast to assemble, as well as with the possibility of simple and quick expansion depending on the needs of users. The article shows the main idea of the advanced large format 3D printing for geopolymers with using an ergonomic printing method as well as materials research in modern filaments in the form of geopolymers.
Abstract
The article presents the first results of the project under the title: ‘Development of 3D printing technology for construction and facade prefabricated elements made of [...]
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Concrete Durability Probed Using Compressive Strength, Chloride Penetration and Porosity Measurements on CEMII and CEMV Concretes Incorporating Mollusc Shell Spares in Artificial and Natural Seawaters
M. Georges, A. Bourguiba, N. Sebaibi, D. Chateigner, M. Boutouil

DBMC (2020).

Abstract
The purpose of this study is to improve the recruitment of flat oyster larvae, an endangered species, by means of a specific marine infrastructure made of concrete. This work aims to develop and optimize concrete formulations by varying the type of cement and introducing shellfish by-products into their composition and determine which concrete formulation is the most sustainable to marine organism colonization. Indeed, it is essential to obtain a sustainable concrete submitted to aggressive marine environment (chloride ions diffusion and bio-colonisation). Four concrete formulations were tested with two types of cements (CEMII and CEMV) and with or without the incorporation of shell aggregates. The durability of these materials was tested after 3 months of immersion in the Rance of Dinard (France). It appears from this study that the CEMII concrete exhibits a good mechanical resistance independently of the presence of shell, after immersion in situ. This concrete also shows better resistance to chloride ions diffusion than CEMV. However, CEMV possess larger compressive strengths than CEMII, and mollusc shells incorporation does not decrease this strength as much as for CEMII. Shell incorporation in the concretes has an effect on strength, chloride penetration and porosity which depend on the used cement and seawater.
Abstract
The purpose of this study is to improve the recruitment of flat oyster larvae, an endangered species, by means of a specific marine infrastructure made of concrete. This work [...]
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Effect of Carbonation in Mortars with Different Types of Metakaolin and Curing Procedures
H. Carasek, M. Jungblut, P. Passos, O. Cascudo

DBMC (2020).

Abstract
This study aimed to evaluate the influence of different types of metakaolin and curing conditions on mortars depth of carbonation. To do so, prismatic mortar specimens were produced by using three different 1:2 mix proportions (binder: sand): a reference mix proportion (without mineral addition) and two mixes with partial replacement of the cement by metakaolin, in the content of 10% by mass of cement. Two types of metakaolin with different characteristics were used in order to verify their capacity of changing the mortar microstructure and the pore solution, modifying this way the carbonation behavior of these materials. Three curing conditions for the test specimens were defined: no wet curing and wet curing (by immersion in water) for 3, 9 and 28 days. After the accelerated carbonation procedure in a CO2 chamber (in an atmosphere of 10% of CO2), with a relative humidity of 70% and a temperature of 20°C, for a period of 7 days, the carbonation depth was measured by using pH-indicators based on phenolphthalein and thymolphthalein. The results indicated influence of the type of curing in the carbonated depth and the significant interaction between curing and the type of metakaolin. When wet curing was not performed, the carbonation was more intense in the reference mortar. The effect of curing in the mortars with metakaolin was much less significant compared to that in the reference mortar. A global discussion about carbonation behavior of metakaolin modified mortars will be performed, based on the characteristics of the metakaolins.
Abstract
This study aimed to evaluate the influence of different types of metakaolin and curing conditions on mortars depth of carbonation. To do so, prismatic mortar specimens were [...]
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Influence of the Particle Size Distribution of Natural Sands in the Accelerated Alkali-Silica Expansion Test (AMBT)
P. Vila, M. Pereyra

DBMC (2020).

Abstract
The accelerated mortar bar test (AMBT) is used to evaluate the potential expansion of the aggregate for the alkali-silica reaction. In this test, the aggregate should meet a certain distribution of particle size. In Uruguay it is usual that for concrete the fine aggregate is constituted by a mixture of sands, one of coarse size and another of fine size. Therefore, coarse sand must be crushed for the test and the fine sand is weighted accumulated in the smallest sieve in which there is enough material according to its particle size distribution. The aim of the work is to evaluate the influence of the particle size distribution of natural coarse sands, without crushing, in the result of the AMBT test. Mortars with different grading composition and single particle size were elaborated, and the differences obtained in the expansion, in the formation of efflorescence on the surface of the bars and in the presence of the reaction gel in the solution where the bars were immersed were analyzed. A greater expansion was observed in the samples with a continuous size distribution, compared with a single particle size. In addition, in the bars elaborated with the largest particle size, a greater amount of gel on its surface and in the solution was observed. The relevance of the work was to improve the reliability of the result in the AMBT test to evaluate the reactivity of the natural coarse sand. Natural sands of siliceous quartzfeldespathic origin were evaluated, without pessimum effect.
Abstract
The accelerated mortar bar test (AMBT) is used to evaluate the potential expansion of the aggregate for the alkali-silica reaction. In this test, the aggregate should meet [...]
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Behavior of Waterproofing Systems Exposed to Environmental Agents
J. Braun, F. Maranhão, R. Monte

DBMC (2020).

Abstract
The service life of buildings can be associated with the durability of enveloping the elements, e.g., the flat roofs that are constantly exposed to environmental agents. Waterproof membranes, produced with bituminous or polymeric materials, usually protect these elements. This paper presents an experimental study of waterproofing systems subjected to environmental agents of degradation. Four types of membranes were tested: bituminous, polyurethane, acrylic and acrylic with polyester mesh. All membranes were applied to concrete substrates and exposed to cycles of 48 hours in 70°C oven and 24 hours in immersion vats with 23°C water. The specimens were subjected to 0, 4, or 8 cycles and submitted to pull-off tests. The results demonstrated that the waterproof system behavior change when subjected to cycles of the temperature gradient. The tests show that the different thermal deformation between the membranes and the concrete substrate results in loss of adhesion.
Abstract
The service life of buildings can be associated with the durability of enveloping the elements, e.g., the flat roofs that are constantly exposed to environmental agents. Waterproof [...]
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Evaluation of the Effects of Environmental Exposure on the Performance Decay of ETICS
M. Nicolella, R. Landolfi, A. Pino

DBMC (2020).

Abstract
The performance decay of a building component is influenced by a huge variety of parameters, interacting between them and determining different results in terms of service life and performance over time. For this reason, evaluating and modeling the performance of a component requires the comprehension of the way and the measure the single factors affect it, and turning this into an analytical model is a very complex operation. Moreover, components of existing buildings are subjected to an additional incognita: the characteristics and the durability of the materials, which is hardly a certain information, and can vary between similar buildings, affecting the accuracy of the evaluation. This study, conducted according to the guidelines of ISO 15686:7 code, investigates on a common solution for interventions on existing buildings, the ETICS, surveying their current performance degree through thermographic camera tests. The aim is to appreciate the difference in the performance decay between different façades of the same building - a homogeneity that allows to estimate this parameter alone - in order to reach an analytical expression of the variation of performance decay according to the difference in the exposure. The sample is constituted by buildings of large dimensions and well-known original projects and details of successive interventions, located in the city of Naples. The data obtained with in-field measurements were subjected to statistical analysis, to allow the quantitative determination of the impact of this parameter.
Abstract
The performance decay of a building component is influenced by a huge variety of parameters, interacting between them and determining different results in terms of service [...]
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Durability of Internally Insulated Historical Solid Masonry Under Future Climates: A Stochastic Approach
S. Sahyoun, L. Wang, H. Ge, M. Defo, M. Lacasse

DBMC (2020).

Abstract
Today, it is globally known that climate change needs to be addressed to mitigate its harmful effects on our environment. It is also common knowledge that the contribution of historical buildings to the energy consumption of the existing Canadian building stock is severe. Buildings of historical identity are often poorly thermally insulated. Thus, to increase energy efficiency and occupant comfort in cold climates, the application of thermal insulation on the interior side of solid masonry walls offers a possibility to improve the historic buildings’ energy performance, without compromising their identity and cultural heritage values. As a result, the historical masonry will be subjected to lower temperature during the heating season, which can increase the potential for condensation and frost within the wall. A balance must therefore be reached between durability measures and thermal performance objectives. This paper intends to achieve this balance through determining the impact of the interior insulation thickness on the durability of a typical historical masonry wall under the effect of climate change. A stochastic approach is used in hygrothermal simulations to account for the uncertainty in material properties. Results in Ottawa indicate a higher risk to frost damage after interior insulation is added to a brick wall having a moisture critical degree of saturation (Scrit) of 0.25 and 0.35. Moreover, both deterministic and the stochastic results were in good agreement. Also, both methods showed an increase risk to frost damage under a changing climate.
Abstract
Today, it is globally known that climate change needs to be addressed to mitigate its harmful effects on our environment. It is also common knowledge that the contribution [...]
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The Stone Masonry Contribution in Greek Industrial Buildings’ Typology and Construction Durability (Late 19th to Early 20th Century)
G. Cheirchanteri

DBMC (2020).

Abstract
Stone masonry is the oldest form of construction in the world until the beginning of the 20th century. The first stone walls were constructed by farmers and primitive people by piling loose field stones into a dry stone wall. Later, mortar and plaster were used, especially in the construction of city walls, castles, and other fortifications before and during the Middle Ages. These stone walls are spread throughout the world in different forms. Stone walls are usually made of local materials varying from limestone and flint to granite and sandstone. However, the quality of building stone varies greatly, both in its endurance to weathering, resistance to water penetration and in its ability to be worked into regular shapes before construction. Also, the majority of buildings in Greece at the end of 19th century up to the use of concrete in constructions are load-bearing stone masonry structures. Moreover, research shows that it is the most widely construction material in industrial buildings, that era. As it is known, stone masonry has high compression strength under vertical loads but has low tensile strength (against twisting or stretching) unless reinforced, while the tensile strength of masonry walls can be increased by thickening the wall. In general, industrial buildings constructed of stone masonry, from late 19th to early 20th century, have particularities in their typology because they were directly dependent on their mechanical equipment and production line. The aim of this study is to investigate the contribution of stone masonry as a construction material in the typology of these industrial buildings concerning their durability.
Abstract
Stone masonry is the oldest form of construction in the world until the beginning of the 20th century. The first stone walls were constructed by farmers and primitive people [...]
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On the Effects of Relative Humidity and CO2 Concentration on Carbonation of Cement Pastes
Q. Phung, A. Varzina, J. Perko, D. Jacques, N. Maes, Ö. Cizer

DBMC (2020).

Abstract
Many environments to which concrete is exposed are highly aggressive due to various chemical components. In such environments, concrete is subjected to processes of chemical degradation, among which carbonation is one of the most frequently seen degradation processes. Though, the influence of saturation degree (or relative humidity - RH) of the specimen and CO2 concentration on the carbonation of cementitious materials is still not comprehensively described with respect to carbonation rate/degree as well as alteration in microstructure and mineralogy. This work aims at thoroughly investigating how these two key parameters affect the carbonation under accelerated conditions. Furthermore, the effect of initial moisture state of the specimen on the carbonation rate is also demonstrated. For such purpose, a numerical model at continuum scale is developed to investigate the effects of RH and CO2 concentration on the carbonation depth, phase changes in phases and porosity of hardened cement pastes due to carbonation under accelerated conditions. Verification with experimental results from accelerated carbonation tests shows a good agreement. The modelling results with supporting experimental data help to better understand the modification of material properties under different carbonation conditions and to optimize the carbonation conditions.
Abstract
Many environments to which concrete is exposed are highly aggressive due to various chemical components. In such environments, concrete is subjected to processes of chemical [...]
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Metamodel Development for Predicting Hygrothermal Performance of Wood-Frame Wall under Rain Leakage
L. Wang, H. Ge, L. Wang

DBMC (2020).

Abstract
In recent years, stochastic modeling has been increasingly applied to investigate the uncertainties of input parameters in hygrothermal simulation and the moisture damage risks of building envelopes. Generally, stochastic modeling requires hundreds or even thousands of simulations to take into account the uncertainties of input parameters, which is computationally intensive and timeconsuming. This paper aims to apply polynomial and neural network metamodel as a substitute for the traditional hygrothermal model, to predict the hygrothermal performance of building envelopes. In the previous study carried out by the authors, stochastic simulations have been performed based on the traditional hygrothermal model, to investigate the hygrothermal performance of wood-frame walls under different rain leakage levels. The material properties and rain deposition factors were considered as stochastic variables, and stochastic simulations were performed under three rain leakage scenarios: 1%, 0.5% and 0.1% of wind-driven rain. In this paper, the stochastic inputs (the hygric material properties and rain deposition factor) and outputs (the maximum moisture content and mold growth index over a 5-year period of the simulation) of a conventional 2×6 wood-frame wall are used to develop the metamodels through polynomial regression and neural network methods. The metamodels are developed for each rain leakage scenario, and the stochastic data of the three rain leakage scenarios are aggregated together to train another metamodel. It is found that the metamodels generally perform well to predict the maximum moisture content and mold growth index. The metamodels for low rain leakage scenarios are better than those for high rain leakage scenarios and the neural network metamodel is more accurate than polynomial metamodel for high rain leakage scenarios, i.e. 1% of rain leakage.
Abstract
In recent years, stochastic modeling has been increasingly applied to investigate the uncertainties of input parameters in hygrothermal simulation and the moisture damage [...]
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Influence of Surface Treatment of Fresh Concrete on its Resistance to Drying Shrinkage
P. Reiterman, V. Davidová

DBMC (2020).

Abstract
The volume changes of cement-based composites are significantly exhibited during the hardening process. Initial phases of the hardening are complemented by the expansion due to the heat evolution that is subsequently alternated by the shrinkage. Both could cause the crack initiation causing significant loss of the durability and service-life shortage. The present paper focuses on the experimental investigation of the surface treatment of fresh concrete, which is applied to prevent sudden loss of the moisture during a hardening process, especially during the concrete highway construction. The technology of concrete highway production is extremely costs demanding, but its efficiency is determined by the longer lifespan in comparison with the asphalt pavement. However, negative impacts of the drying shrinkage could significantly reduce the durability. The efficiency of used treatment was investigated in terms of restrained shrinkage tests, water adsorption and mechanical testing. In addition, there were studied two types of conventional Portland cement. Performed program confirmed great sense of the curing on the concrete durability; in addition, there was well illustrated the efficiency of the utilization of blended binder systems in the paper.
Abstract
The volume changes of cement-based composites are significantly exhibited during the hardening process. Initial phases of the hardening are complemented by the expansion due [...]
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Pathologies of a Glass Building Envelope that Affect Durability and Comfort
S. Santamaria-Fernandez, A. Eizaguirre-Iribar, X. Olano-Azkune

DBMC (2020).

Abstract
The durability of materials used in buildings has been widely studied and, in many cases, there are standards to assess it. However, studies on how pathologies affect the durability and comfort of the building users are not so common. The aim of this article is to explain different pathologies of the building envelope, considering glass as its main element and to analyze the causes of those pathologies, agents involved, and how they have affected durability. For that purpose, different cases of pathologies were analyzed on-site, both during the construction process and during the final use of the building. The effects of the different pathologies were also assessed. In each case, the technical data sheets available of the materials involved and the information on the design and the expected performance of the constructive solution were compiled. In some cases, the pathologies had caused an irreversible damage, so, the solution had to be drastic; while in other cases, they were detected early enough to propose remedial actions without affecting the final durability of the building. After having analyzed the different cases, the agents causing the pathology or those responsible for it and the phase in which the pathology occurred were identified. As a result, remedial actions were proposed to avoid the generation of pathologies during the design, construction and maintenance processes that affect the durability of the building and their user‘s comfort.
Abstract
The durability of materials used in buildings has been widely studied and, in many cases, there are standards to assess it. However, studies on how pathologies affect the [...]
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Dynamic Observability Method for Durability Assessment Considering Measurement Noise
T. Peng, J. Casas, J. Turmo

DBMC (2020).

Abstract
Due to the inevitable degradation of material properties in structures in daily use, such as stiffness degradation due to cracking in concrete elements, their durability will definitely be influenced, and their serviceability and safety could be in danger. Thus, understanding and identifying the change in the structural parameters provides new approaches to evaluate their durability. Structural system identification by dynamic observability method, which is using subsets of masses, natural frequencies and modal shapes, is a powerful tool to detect the change of structural parameters. Taking into account the presence of noise in the measurement data in real world structures, this method establishes the relative dynamic equation with the error separation items. The equation is solved by error minimization of an objective function combining the measured frequencies and mode shapes through the parameter MAC (Modal Assurance Criterion). Additionally, the algorithms and the steps are introduced based on the dynamic eigenvalue equation, which can fully demonstrate the performance of observability techniques. The present paper provides an example on how to successfully identify structural parameters. Its suitability for practical applications is demonstrated in a large frame structure. The result is a much more accurate identification of the parameters involved in the durability of the structure even in the case of noise-corrupted measurement signals.
Abstract
Due to the inevitable degradation of material properties in structures in daily use, such as stiffness degradation due to cracking in concrete elements, their durability will [...]
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Methodology for Predicting the Service Life of Two-Ply Roofing-Felt Membrane
E. Brandt, M. Morelli

DBMC (2020).

Abstract
The service life of roofs depends not only on the quality of materials and components but also on several other factors such as workmanship, maintenance, design and substrate. The service life of materials is at production time estimated to a certain number of years. Later when some experience has been gained the service life can hopefully be better predicted. However, the predicted service life can always be questioned because no one knows how long the product or material will last. The durability of a two-layer roofing-felt membrane has been investigated through inspection of several 20 to 30 years old roofs that had aged naturally under in use conditions in a northern humid climate. In 50 % of the inspected roofs, samples were taken out for laboratory test. In this paper, the developed methodology to conduct a service life prediction of roofing membrane is presented. The paper includes a description of the on-site inspection; test conducted in the laboratory which was used as basis for predicting the service life of the two-layer roofing-felt membrane and how these information are extrapolated to a predicted service life. Further, it is discussed if the used methodology for prediction is generally applicable for other types of membranes.
Abstract
The service life of roofs depends not only on the quality of materials and components but also on several other factors such as workmanship, maintenance, design and substrate. [...]
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Resistivity Measurements to Assess the Freeze - Thaw Attack on Concrete - Lab Specimen and Real Structure
F. Spörel

DBMC (2020).

Abstract
Waterway structures like locks are exposed to a severe freeze-thaw-attack. A sufficient resistance of concrete against this exposure has to be assured. In Germany the concrete for the exposure class XF3 of federal waterway structures has to be tested in the laboratory by the CIF-Test in addition to descriptive requirements. To establish this procedure experiences on concrete mix designs which have been applied in the past were considered as well as research concerning the transferability of laboratory tests to practical experience. One important aspect was a service life study on the degree of water saturation of the concrete under practical conditions in combination with the temperature exposure. The paper presents the results of freeze-thaw tests on lab specimens and cores of concrete elements stored differently and tested at different ages. For a better understanding of the processes of the freeze-thaw attack during the freeze-thaw tests monitoring data of resistivity has been analyzed and compared to hardened concrete properties. The water absorption inside the specimen during capillary suction and the freeze-thaw-cycles could be monitored at different distances to the surface. Correlations of the water absorption to the initiation and development of internal damage were observable. A consideration of the results of the freeze-thaw tests and the resistivity measurements enables a better evaluation of long-term resistivity monitoring data of a lock. It allows for an assessment of the transferability of results of the CIF-Test to practical experience.
Abstract
Waterway structures like locks are exposed to a severe freeze-thaw-attack. A sufficient resistance of concrete against this exposure has to be assured. In Germany the concrete [...]
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How to Determine when a New Building Product is Suitable - Certifications and Experience
E. Hansen, ø. Nielsen, E. Møller, R. Peuhkuri

DBMC (2020).

Abstract
Previously, only solutions with long-term experience were used in the building sector and it was sufficient to describe, e.g. in the building regulations, how they should be constructed. However, the innovation rate has gradually increased, encouraged by industrialization and by building regulations becoming more functional based. As a result, the required performance is often described for the whole building or for a building component, but not at product level. Furthermore, CE marking makes it possible to market and sell a product in any country within the European Union if only one or a few properties are declared, and these may even not be the most relevant ones for a specific application in a technical solution. A CE mark is therefore neither a quality mark nor an approval of the product for a specific application, although clients and consultants often believe this is the case. It is therefore a major challenge for the building sector to determine if a new building product is suitable in a specific technical solution (wall, roof, etc.). The paper identifies a gap between performance-based requirements for a technical solution and specific requirements to properties of building products. Two cases (flat roofs with no slope, MgO-containing boards used as wind barriers) show the possible economic consequences of not closing this gap; the technical solution failed, as one of the products was not suitable for Danish weather conditions. The first case initiated the formation of the Danish Building Defects Fund in 1986, the second one from 2015 shows that the gap still exits, 30 years later. The cases show how difficult it can be even for professionals to understand different certifications, especially when a product seems to be well suited for a specific use. Based on the cases, the paper presents a systematic approach that guides users through important issues relating to requirements for a moisture-safe building envelope.
Abstract
Previously, only solutions with long-term experience were used in the building sector and it was sufficient to describe, e.g. in the building regulations, how they should [...]
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Detection Sensitivity of Iron-Foil Corrosion Sensor in Simulated Concrete Solution
A. Eriguchi, H. Fujiwara, H. Itaya, T. Wakabayashi, S. Otani, Y. Isaka

DBMC (2020).

Abstract
This examined the performance of the iron-foil sensor in concrete and its relationship with the amount of chloride in the solution simulating concrete. The corrosion sensor reacted at a chloride ion concentration of 500 ppm. From the results, it was inferred that the sensor has a high sensitivity. Furthermore, to evaluate the performance of the sensor, it was built a wireless system using radiofrequency identification (RFID), embed it into an actual concrete structure, and subsequently initiate observation.
Abstract
This examined the performance of the iron-foil sensor in concrete and its relationship with the amount of chloride in the solution simulating concrete. The corrosion sensor [...]
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Quality Evaluation of Granulated Blast Furnace Slag Sand Via Acid Immersion and Freeze-Thaw Tests
T. Kawato, I. Kurashige

DBMC (2020).

Abstract
In recent years, the use of granulated blast furnace slag (GBFS) sand as fine aggregate in concrete has been increasingly discussed from the viewpoint of environmental impact reduction and effective utilization of by-products in Japan. The various physical properties of concrete with GBFS sand, such as the compressive strength, drying shrinkage, and carbonation, were evaluated. Especially, it was demonstrated that GBFS sand can modify the hardened cement paste around it owing to the reaction of amorphous phase in the sand. Moreover, its resistance to sulfuric acid is considered to be as excellent as that of BFS powder. Therefore, in this study, we attempted to evaluate the performance of GBFS sand using a freeze-thaw (F-T) and acid immersion tests. Consequently, it was found that GBFS sand mortar had a significantly higher resistance to F-T and sulfuric acid than crushed sand mortar. In addition, it improved the resistance to freezing and thawing by prolonged curing. In our experiments, the resistance of GBFS sand mortar to sulfuric acid was measured to be approximately four times higher than that of crushed sand mortar. In contrast, in the case of nitric acid, the ratio was measured to be only two times higher. From the above results, it was concluded that the performance of GBFS sand can be easily judged by F-T and sulfuric acid immersion tests.
Abstract
In recent years, the use of granulated blast furnace slag (GBFS) sand as fine aggregate in concrete has been increasingly discussed from the viewpoint of environmental impact [...]
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Observations of Moisture Damages in Historic and Modern Wooden Constructions
S. Ott, P. Aondio

DBMC (2020).

Abstract
With the introduction of new building products made of planar glued board lamellas, the CLT, the restriction of load-bearing structures to linear and thus additively used load-bearing members was abolished. As a result, new, technically determined boundary conditions for moisture management in the interior of buildings have arisen. Due to the emergence of massive, planar wall and floor components as in concrete construction, the integration of building services technology in timber construction must now take place differently than was traditionally the case. In addition, it can be observed that the damage to building components is increasing, the detection of moisture damage is becoming more difficult and, ultimately, the consequences and risks are not yet foreseeable. The study focuses on the cause-effect relationship of increased water input and uses selected examples to reveal the problem of moisture exposure in the interior of buildings with planar load-bearing structures, the damage mechanisms and direct consequences set in motion. This paper shows the necessity for moisture protection measures in modern timber structures in comparison to traditional ways to construct with timber. It shows where moisture intake with modern structures must be considered and avoided from the engineering perspective in order to minimize the risk of moisture damage.
Abstract
With the introduction of new building products made of planar glued board lamellas, the CLT, the restriction of load-bearing structures to linear and thus additively used [...]
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Long-term Performance of Repairs to Reinforced Concrete Exposed to Coastal Conditions
S. Sato, Y. Masuda, M. Kakegawa

DBMC (2020).

Abstract
Reinforced concrete (RC) specimens were treated using different combinations of surface coating and/or patch repair methods and materials, left in a coastal region with frost damage risk, and their properties characterized after 25 years of exposure. Specimens were prepared by chipping away concrete from one section of concrete block with embedded reinforcement bars to expose the bars, followed by patch repair and then surface coating. Four types of material were used for patch repair: cement mortar, styrene-butadiene rubber (SBR) polymer cement mortar, rust-resistant SBR polymer cement mortar, and lightweight epoxy mortar. Two types of material were used for surface coating: multi-layer textured and thin textured coating. Following exposure, cracks were visible only on the surfaces of untreated specimens, apparently due to rebar corrosion; they were absent from all specimens that had undergone surface coating and/or patch repair. In addition, the corrosion resistance of these methods and materials was investigated by measuring and comparing the surface areas of corroded rebar between three segments: the repaired part, the unrepaired part, and the boundary between them. Concrete carbonation and rebar corrosion were greatly dependent on surface coating material, with the multilayer-textured coating especially effective at blocking chloride penetration. In addition, rebar corrosion was more effectively prevented by patch repair with the SBR polymer cement mortar than with the lightweight epoxy mortar.
Abstract
Reinforced concrete (RC) specimens were treated using different combinations of surface coating and/or patch repair methods and materials, left in a coastal region with frost [...]
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Development of a Service Life Database of Building Elements Based on an International Data Collection
K. Goulouti, M. Giorgi, D. Favre, S. Lasvaux

DBMC (2020).

Abstract
This paper presents a new service life database (DUREE database) for building elements, based on international service life data. The database includes 7‘000 service life data, for more than 2‘000 building elements. In addition, the fitting of the data to a lognormal distribution is presented. The study contributes to the increasing demand of probabilistic building LCA and LCC and provides the possibility to define statistical distributions, with a systematic way, for a large number of building elements and different levels of details (LOD), appropriate for BIM-based assessments.
Abstract
This paper presents a new service life database (DUREE database) for building elements, based on international service life data. The database includes 7‘000 service life [...]
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The Impact of Climate Change on Material Degradation: Finding a Feasible Approach for Climate Model Evaluation
H. Hedayatnia, N. Bossche

DBMC (2020).

Abstract
Understanding how climate change accelerates or slows down the process of material deterioration is the first step towards assessing adaptive approaches for the preservation of historical heritage. Analysis of the climate change effects on the degradation risk assessment parameters like freeze-thaw cycles and salt crystallization is also a key parameter when considering mitigating actions. Due to the vulnerability of cultural heritage in Iran to climate change, the impact of this phenomenon on basic parameters like temperature was analyzed. Choosing an appropriate regional climate model is the first and most crucial step in the analysis of climate change effects on heritage. The outputs of two different regional climate models: the ALARO-0-SURFEX model (Ghent University, Belgium) and the REMO model (HZG-GERICS, Germany) were analyzed to find out which model is more adapted to the region. So the focus of this research is mainly on the evaluation process to find a feasible approach for validation study to determine the reliability of each model. For model validation, a comparison between model data and observations was performed for 30 years from 1980-2017. Besides, some climatic parameters which are likely critical for heritage like freeze-thaw cycles were studied to find out how reliable these models are in the field of building pathology.
Abstract
Understanding how climate change accelerates or slows down the process of material deterioration is the first step towards assessing adaptive approaches for the preservation [...]
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Durability Assessment of Gypsum Boards with Glass Mat Reinforcement Used in Light Facade Systems
M. Resende, D. Meirelles, G. Boriolo, L. Oliveira

DBMC (2020).

Abstract
Gypsum boards with glass mat reinforcement are used in light weight facade systems. These boards were recently brought to the Brazilian market. Therefore, there are few studies and little practical knowledge of their performance over time, mainly concerning to durability. The gypsum boards manufacturers set that these boards always need to be coated, however they can be exposed to natural conditions during the construction site period. A study is necessary to evaluate the feasibility of using these boards in Brazil, since the exposure conditions relating to humidity, temperature and solar radiation are different from Europe and North America. The aim of this paper is to show the approach used to evaluate the durability of the gypsum board with glass mat reinforcement, and also show the test results. In order to establish the durability approach, standards were adopted, as well as the functional performance concept. In addition, the tests considered that such boards would be used on the facade and should behave similarly to other boards used in facades in Brazil, such as fiber cement boards. Thus, mechanical tests were done in steady state, saturated and after aging in cycles of immersion, drying and heating. Other evaluations were made on gypsum boards applied on exposed walls. The results showed that even the board strength decreases after the accelerated aging cycles, the final value remains in an acceptable level. In addition, boards applied on exposed walls for 12 months have been presenting a good performance; meaning no cracks neither detachments, even though the follow-up still needs to be maintained longer.
Abstract
Gypsum boards with glass mat reinforcement are used in light weight facade systems. These boards were recently brought to the Brazilian market. Therefore, there are few studies [...]
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A Spatially Continuous Driving Rain Map of India at 0.5°×0.5° Gridded Scale
S. Das, K. Sarkar

DBMC (2020).

Abstract
Driving rain is one of the most critical sources of moisture affecting the hygrothermal and durability performance of building envelopes. The estimation of severity in terms of annual driving rain indices using annual and monthly weather data (aaDRI and maDRI respectively) aids towards contemplating potential moisture loads, and hence in the efficient design of buildings in the geographical area of interest. In this study, monthly and annual gridded datasets of wind and rainfall, pertaining to the thirty-year period of 1988-2017 have been used to design a spatially continuous driving rain map for India at 0.5°×0.5°(lat./long.) resolution. The observations reveal that the use of annually averaged data leads to underestimation of the driving rain severity thereby highlighting the inefficiency of a coarser temporal scale. A linear relationship has subsequently been developed to enable refinement of aaDRI into maDRI. The analysis of the monthly driving rain map reveals that the entire western coastal belt and a few regions in the north-eastern part of the country observe high to severe exposure conditions. Furthermore, a trend analysis of the yearly driving rain index values reveals statistically significant decreasing trends over the northern and eastern regions of the country, whereas increasing trends in the shielded regions surrounding central India is observed.
Abstract
Driving rain is one of the most critical sources of moisture affecting the hygrothermal and durability performance of building envelopes. The estimation of severity in terms [...]
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Experimental Study on Carbonation Resistance and Water Absorbing Property of Concrete Crack with repair
N. Tsuchiya, K. Nemoto

DBMC (2020).

Abstract
Existing RC Buildings have some cracks and the repairing service might last the buildings for long life. The durability of the RC component is evaluated by several ways as like as carbonation resistance test, permeability test, water penetration test, and so on. Therefore, it need to be measured how much advantage the concrete crack with repair have for the durability. The aim of this paper is to study on advantage of repairing a crack of concrete to the carbonation resistance and the waterabsorbing property by the experimental way. The specimens were prepared in the following point. The finishing (direct finishing and mortal tile finishing), crack width (0, 0.05, 0.5, and 2mm), and choice repairing or not. All concrete specimens were formed 10 x 10 x 20cm and those W/C were 0.55. Then, the specimens were tested by the accelerated carbonation. After 4, 8 and 26weeks accelerated carbonation, the carbonation depth and the carbonation shape of the concretes were measured by 1% phenolphthalein reaction. Also, the amount of absorbed water from the bottom were measured at 1, 3, 6, 24, 48, 72 and 168h. From the results, the carbonation went rapidly located in 2cm around the crack in the case of the no-repair specimens, regardless of any finishing. But in the case of the specimens repaired, it went evenly from the exposure side. And water absorbing test results show a trend that water amount of the concrete with a crack more increase than one of the no-crack concrete.
Abstract
Existing RC Buildings have some cracks and the repairing service might last the buildings for long life. The durability of the RC component is evaluated by several ways as [...]
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Statistical Analysis of Sulfate Attack Resistance of Reactive Powder Concrete
U. Bektimirova, E. Sharafutdinov, C. Shon, D. Zhang, J. Kim

DBMC (2020).

Abstract
This paper is the study of sulfate attack resistance of reactive powder concrete (RPC). RPC that is also known as ultra-high performance concrete is a special type of concrete material obtained when fine powders like silica fume (SF) are added into the concrete mortar along with very low waterto-binder ratio (w/b). SF is a pozzolanic material obtained as a by-product of silicon metal or ferrosilicon alloys production. In this study, total 6 different RPC mixtures with various w/b (0.18, 0.22 and 0.26) and various SF content were studied. SF was added into the concrete mixtures in the amount of 15%, 20% and 25% of cement by weight. The other testing parameter includes 3 different concentrations of sodium sulfate (Na2SO4) solutions (0.35 M, 0.7 M and 1.4 M concentrations). Broad laboratory investigations of behavior of the RPC mixtures were conducted in terms of compressive strength and mass gain of cubes (50×50×50 mm3) and expansion and mass change as in accordance with ASTM C1012. Test results had been analyzed and assessed by Taguchi method. The significance level of experimental parameters was determined by using Analysis of variance (ANOVA) method. According to statistical and analytical results it was observed that RPC has high sulfate attack resistance. Moreover, addition of optimal amount of SF into the RPC mixtures as well as decreasing w/b can significantly improve Na2SO4 resistance of RPC.
Abstract
This paper is the study of sulfate attack resistance of reactive powder concrete (RPC). RPC that is also known as ultra-high performance concrete is a special type of concrete [...]
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Intrinsic Differences on the Photodegradation Mechanisms between Pigmented and Non-Pigmented Coatings Determined by Multi-Scale Analysis
T. Ishida, R. Kitagaki, H. Hagihara, Y. Elakneswaran

DBMC (2020).

Abstract
Multi-scale analysis of photodegradation are conducted for pigmented coating containing acrylic urethane + TiO2 pigment and for non-pigmented coating containing only acrylic urethane. We discuss the intrinsic differences in the photodegradation mechanism between the pigmented and nonpigmented coatings and the effect of the interface between the pigment and the binder. Photo-aging tests are conducted using artificial ultraviolet (UV) irradiation under conditions of 60 °C and dry atmosphere. The results of Fourier transform infrared spectroscopy (FTIR), solvent swelling experiments, ultrasonic measurements of elastic moduli, and colourimetry used for material characterisation before and after photo-aging. Although the behaviour of E and the carbonyl index (CI) show common trends for both samples, the overall trends of yellowness index (YI) and swelling degree (Q) differ significantly between the pigmented and non-pigmented samples. The results reveal that changes in macroscopic properties may not necessarily correspond with the CI behaviour and that characteristic interfacial effects exist between the pigment and the binder. The onsets of coating erosion and chalking are observed in the pigmented coating as surface topological changes. The different behaviour of YI and Q between the sample types can be attributed to the interfacial effect at pigment/binder interface based on the photocatalytic effect from TiO2 pigment
Abstract
Multi-scale analysis of photodegradation are conducted for pigmented coating containing acrylic urethane + TiO2 pigment and for non-pigmented coating containing only acrylic [...]
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Ionic Diffusivity and Pore Structure of Hardened Cement Paste Exposed to High Temperature Environment for Long Period
I. Kurashige

DBMC (2020).

Abstract
Ion diffusion through cement-based barrier is key to safe radionuclide transfer in intermediate radioactive waste disposal facilities. The purpose of this research is to elicit the behavior of ionic diffusivity and pore structure of hardened cement paste specimens for the barrier system when exposed to high temperatures (up to 80°C) for long periods (up to one year). The cement paste is made of an ordinary Portland cement base- and a low-heat Portland cement / fly ash / limestone filler (LF)system. The results of the adsorption isotherms of N2 and water vapor of the specimens exposed to limesaturated water of different temperatures, 20, 40, 50, 60, and 80°C, are presented, and their pore size distributions are analyzed by the Barrett-Joyner-Halenda method. The change of specific surface areas is measured and the influence of high temperature on the pore structure is discussed. Additionally, results of chloride ionic diffusivity test for the specimens after the high-temperature exposure are contrasted with the tendency of pore structure change. It is found that the LF system has much higher resistance to high-temperature exposure than ordinary Portland cement; however, temperatures greater than or equal to 60°C deteriorate the ionic diffusivity. These experimental results may indicate the ionic diffusivity of hardened cement paste can be influenced by the spatial electrical charge in micropores depending on the electrical charge of pore wall and the ion composition of pore solution.
Abstract
Ion diffusion through cement-based barrier is key to safe radionuclide transfer in intermediate radioactive waste disposal facilities. The purpose of this research is to elicit [...]
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Use of Steel Fiber Reinforced Concrete for the Protection of Buildings Against High Dynamic Actions
V. Zohrabyan, T. Braml, T. Zircher, M. Keuser

DBMC (2020).

Abstract
Nowadays ensuring the safety of people and the protection of infrastructure is a socially relevant topic, which requires a thorough investigation. The Institute of concrete construction at the University of the German Armed Forces in Munich is investigating the possibilities of using steel fiber concrete for the protection of military facilities and state-owned special buildings in Germany. In this research project steel fiber reinforced concrete is investigated under high dynamic loads specifically under contact detonation loading. Plates with varying reinforcement systems, different thicknesses, different fiber geometries, fiber contents and fiber types were produced.The following concrete compressive strengths C20/25, C40/50, C80/95 were used in this research project.The plates were loaded with 500 g, 750 g, 1000 g, 1500 g and 2000 g PETN explosive at the test facility of the German Armed Forces Technical centre for Protective and Special Technologies. An important property of construction material during ballistic threats and contact detonation is the concrete tensile strength. Through the addition of fibers, the post cracking behavior and the ductility of concrete components can be improved. All fiber-reinforced specimens showed less damage than the non-fiber reinforced elements. The aim of the study is to optimize the concrete mixture for the fiber concrete protection components considering the following factors: concrete quality, fiber content, fiber geometry, as well as aggregate size of the concrete. Another aim is to record and evaluate the damage parameters of the steel fiber reinforced concrete slabs after the highly dynamic load, and to investigate to offer suggestion for retrofitting. In this article, the test results of different steel framed concretes under highly dynamic conditions are presented.
Abstract
Nowadays ensuring the safety of people and the protection of infrastructure is a socially relevant topic, which requires a thorough investigation. The Institute of concrete [...]
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Environmental Deterioration Factors in Metal Claddings and GFRC Panels Implemented on Facades: An Assessment through Two Cases in Istanbul
S. Ardi, B. Diker, P. Bahri

DBMC (2020).

Abstract
Decrease in performance of building facades, components, and materials before their service life is an unexpected situation. Therefore, detecting the probable causes of these anomalies plays a crucial role in maintenance planning. This study aims to determine the environmental deterioration factors which affect the performance of buildings, especially building façades, through two case buildings situated in the same university campus in Istanbul. The methodological framework of the study is based on visual observations and literature review. Through observations on a different period of time, anomalies have been detected and photographed. In the first case, it has been focused on metal claddings on building façade. In the second case, it has been focused on GFRC panels which have the majority of the North façade. Within the help of literature and observations, two cases have been compared to each other in terms of their deterioration factors and interpreted through graphs. In the first case, occurred deteriorations have been detected such as uniform dirt, corrosion, joint degradation, mechanical impacts, and delamination. in the second case, deteriorations have been observed such as biological staining, uniform dirt, moisture rising, and design failures
Abstract
Decrease in performance of building facades, components, and materials before their service life is an unexpected situation. Therefore, detecting the probable causes of these [...]
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Analysis of the Variation of Thermal Conductivity of Rigid Polyisocyanurate Foam (PIR) in The Context of Aging
T. Makaveckas, R. Bliūdžius, A. Levinskytė

DBMC (2020).

Abstract
For most building insulation materials, dependency of the thermal conductivity on temperature is close to linear, and it increases with rising materials temperature, but the thermal conductivity of the polyisocyanurate foam (PIR) increases in the lower temperature range, so the heat transfer through the partition insulated with this material is increased in the cold season. The thermal conductivity of PIR also increases during the aging process, especially during the later operating period, which is not covered by the standard aging procedure used to determine the declared thermal conductivity value. Also, there is a lack of information how PIR reacts to the certain temperatures and other climate conditions, and how fast it loses its thermal properties. The aim of this experimental research was to analyse the change of the thermal conductivity depending on aging temperature. 30, 50mm thick PIR samples were prepared for the test, and the thermal conductivity of all specimens was measured at the standard conditions prior to the start of the test using the heat flow meter FOX 314, and again after each stage of aging, when the samples were kept at the certain temperature for 21 days. The results showed that the thermal conductivity of PIR increases more (up to 10 %) when kept at higher temperatures (+50 °C, and +70 °C), and after specimens undergo negative temperatures (-18 °C) it has a minor influence to the change of thermal conductivity of PIR.
Abstract
For most building insulation materials, dependency of the thermal conductivity on temperature is close to linear, and it increases with rising materials temperature, but the [...]
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Study on the Practical Use of Urea to Reduce Drying Shrinkage of Concrete by Spraying Urea Solution under Cold Environment
T. Sato, H. Fujiwara, M. Maruoka, L. Lingling

DBMC (2020).

Abstract
Concrete cracking caused by drying shrinkage adversely affects the durability of a structure. The results of past research has shown that drying shrinkage can be reduced by adding urea as an admixture to the concrete. However, mixing various admixtures at the factory increases the costs for equipment and labor. To reduce drying shrinkage more easily and inexpensively, the urea solution can be applied to the concrete surface by soaking or brushing. However, urea solutions are not suitable for use in cold weather because urea in solution crystallizes at low temperatures. This study attempted to solve this problem by mixing antifreeze, which resists freezing, with a urea solution. It was found that the crystallization temperature of urea can be lowered by mixing the urea solution the antifreeze. Furthermore, it was confirmed that the antifreeze/urea solution reduced drying shrinkage for both mortar and concrete.
Abstract
Concrete cracking caused by drying shrinkage adversely affects the durability of a structure. The results of past research has shown that drying shrinkage can be reduced by [...]
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Monitoring Durability of Limestone Cement Paste Stored at Conditions Promoting Thaumasite Formation
K. Sotiriadis, M. Hlobil, J. Toušek, D. Machová, P. Mácová, M. Vopálenský, A. Viani

DBMC (2020).

Abstract
The durability of Portland-limestone cement with high limestone content was monitored at conditions promoting thaumasite formation. Pore structure and deterioration characteristics were assessed with X-ray micro-computed tomography and correlated with material‘s strength. Changes in crystalline and amorphous phases of the cement paste were investigated with X-ray powder diffraction and solid state nuclear magnetic resonance spectroscopy. Rapid deterioration was observed, evolving as a front causing concentric crack patterns followed by detachment of the part of specimen in contact with the corrosive solution. This ultimately led to loss of structural integrity after 4 months of exposure. During sulfate attack, thaumasite, ettringite and gypsum formed at the expense of portlandite, calcite and monocarboaluminate hydrate. Furthermore, polymerization of silicate chains in C-S-H and deterioration of C-S-H also occurred
Abstract
The durability of Portland-limestone cement with high limestone content was monitored at conditions promoting thaumasite formation. Pore structure and deterioration characteristics [...]
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Higher Incidence Pathologies in Installations of Solar Energy, Gas, Cooling, Heating and Ventilation
M. Carretero-Ayuso

DBMC (2020).

Abstract
This paper focuses on the study and quantifications of pathologies in solar energy, gas, cooling, heating and ventilation installations, based on complaints filed in the courts by the owners of a large number of houses in which errors appeared in those installations. The relevant complaints filed across all of Spain were studied, in what is an important contribution to forensic engineering, given that access to the outcome of civil court cases is seldom obtained. The representativeness of the data is not partial but total, since the entirety of cases existing in the period under study was part of the sample, enabling us to consider this to be a general exposition on the epidemiology of construction pathologies in installations in houses in Spain. It should be noted that the Spanish construction sector is one of the most problematic ones, due to the dissatisfaction generated in homeowners, and as it is one of the ones leading to the highest number of complaints filed with consumer protection bureaus and in the courts. In the investigation, results have been obtained for each of the installations (183 cases in total), according to the type of anomaly (the most important are dysfunctions, leaks and humidity), the pathological origin (poorly arranged encounters, omissions of elements, among others) and the type of construction where it is produced (especially in block dwellings).
Abstract
This paper focuses on the study and quantifications of pathologies in solar energy, gas, cooling, heating and ventilation installations, based on complaints filed in the courts [...]
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Degradation of Concrete Structures from the Climate Change Perspective
P. Benítez, F. Rodrigues, S. Talukdar, S. Gavilán

DBMC (2020).

Abstract
The negative effects of climate change are underway despite the global efforts to mitigate them and the future scenario are unsettling. Climate change poses critical challenges to urban environments and highlights the need for research its impacts on the built environment. One of the most significant effects of climate change on reinforced concrete structures is associated with the carbonation of these structures. The increase of parameters such as temperature and carbon dioxide jeopardise the degradation of such structures by carbonation-induced corrosion. This paper presents the results of the monitoring and analysis of a set of buildings that determine carbonation as the main degradation mechanism of structures in Paraguay. Through the application of a previously developed carbonation model, the worsening of the carbonation-induced degradation has been determined after considering the climate change effects in the coming 50 years. The outcomes of the study determined that the poor quality of the structures in Paraguay cause premature degradation in them. Furthermore, considering climate change effects, it has been determined that this phenomenon could accelerate corrosion failure times in reinforced concrete structures.
Abstract
The negative effects of climate change are underway despite the global efforts to mitigate them and the future scenario are unsettling. Climate change poses critical challenges [...]
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Platform development for drone utilization in the Architectural Field
H. Miyauchi

DBMC (2020).

Abstract
The utilization of drones is expected to streamline the process of building inspection in Japan; however, no known drone utilization platform exists in the region‘s architectural sector. Therefore, in this study we pioneered the development of a drone platform based on an industry- government-academia collaboration within Japan‘s architectural field. We first investigated drone related trends, such as a utilization roadmap, flight rules, the drone market, new technologies and issues relating to the architecture field. Subsequently, we worked on solutions for drone utilization in the building sector, including methods for building inspection, determination of drone-flight risk factors relative to building inspection and the creation of a drone safety operation manual. Through field tests, we validated the effectiveness of the drone platform in building inspection, i.e., the determination of a cost-time relation during inspection, the merits of applying a high-resolution camera for inspection, the possibility of utilizing an infrared camera for exfoliation detection in exterior wall tiles and the development and efficiency of a built-in automatic inspection system. Furthermore, trial tests were conducted for the application of a drone-inspection system in disaster areas and a micro-drone in small building spaces. The findings of this study confirmed that the new drone platform achieved inspection- and disaster-related objectives within the architectural sector.
Abstract
The utilization of drones is expected to streamline the process of building inspection in Japan; however, no known drone utilization platform exists in the region‘s architectural [...]
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Effect of Crack Repair by Bio-Based Materials Using Alginate and Bacillus Subtilis under Wet and Dry Environment Part-I
K. Kawaai, T. Nishida, A. Saito

DBMC (2020).

Abstract
This study examined crack repair methods using alginate gel films (1.5 wt.%) mixed with healing agents under wet and dry actions. The healing agents consist of Bacillus subtilis (natto) as an aerobic microorganism and glucose as an organic carbon source, thereby producing insoluble calcium carbonate in the gel films in the presence of calcium ions. In this study, repaired surface in cracked mortar specimens (50×100mm) was observed by microscope. In addition, water absorption test was carried out in assessing the effectiveness of crack repair for the cases of alginate gel films with or without calcium carbonate precipitation induced by the microbial activities. Based on the observations made by microscope, precipitates in white color were clearly observed after 8 weeks on the cracked surface of specimens especially under wet conditions. In the case of the specimens with higher sealing rate of crack repair, the alginate gel films were remained intact under dry and wet actions, which is advantageous to keep moisture by swelling. Water absorption test was carried out using repaired mortar specimens with average crack size of 0.5 mm. Based on the results obtained, water absorption rate is substantially decreased in the specimens with increasing sealing rate of crack repair. The results suggest that higher crack sealing rate associated with calcium carbonate precipitation leads to higher resistance against water absorption tested in accordance with ASTM C 1585.
Abstract
This study examined crack repair methods using alginate gel films (1.5 wt.%) mixed with healing agents under wet and dry actions. The healing agents consist of Bacillus subtilis [...]
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Effect of Crack Repair by Bio-Based Materials Using Alginate and Bacillus Subtilis under Wet and Dry Environment Part-II
T. Nishida, K. Kawaai, A. Saito

DBMC (2020).

Abstract
This study examined durability of mortar after repairing crack using alginate gel films (1.5wt.%) mixed with healing agents under seawater splayed condition. The healing agents consist of Bacillus subtilis (natto) as an aerobic microorganism and glucose as an organic carbon source, thereby producing insoluble calcium carbonate in the gel films in the presence of calcium ions. In this study, repaired mortar was dried under room condition for half year and exposed at seawater splayed condition for another half year. After that, surface condition, elastic wave velocity was measured. In addition, the inside situation in the crack was observed by X ray computed tomography. Based on the results of elastic wave velocity, the property of repair material in mortar was improved under the seawater splayed condition. Additionally the substance in crack derived from healing agents was remained even after seawater splayed exposure.
Abstract
This study examined durability of mortar after repairing crack using alginate gel films (1.5wt.%) mixed with healing agents under seawater splayed condition. The healing agents [...]
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An Experimental Evaluation of the Thermal Performance of Felt Type Vegetated Facade System
E. Yüksel, N. Türkeri

DBMC (2020).

Abstract
Vegetated facade systems (VFS) have been used as green building envelope systems in recent years. Using VFS for ecological strategies and evaluating thermal performance of these sytems are not a new concept. However, there is not any experimental study in literature which evaluates thermal performance of felt type VFS applied on an insulated existing building wall which is located in Csa climate during cooling and heating periods. Hence, an experimental study was conducted to measure thermal performance of felt type (type which used felt material as growing media) VFS in Kocaeli (under Csa climate). Test results indicate that in day time with high amount of solar radiation, felt type VFS decreased exterior surface temperatures of an insulated existing wall by maximum of 30°C. Also, interior surface temperatures of vegetated facade were lower than interior surface temperatures of reference facade with the maxiumum difference of 1.8°C. Although high differences between exterior surface temperatures of vegetated and reference walls were observed, there was no significant difference between interior surface temperatures of vegetated and reference walls. This is due to the fact that existing building exterior wall assembly includes 5 cm thickness expanded thermal insulation material which enchance thermal performance of brick wall. In addition, indoor air temperatures behind both facades were close to each other, and were not suitable according to ISO 7730 and ASHRAE 55 Standards comfort range for representative summer days with high ambient air temperatures. Nevertheless, indoor air temperatures behind vegetated facade were in the comfort range in the fall representative day which required cooling, while indoor air temperatures behind reference facade were not in the comfort range in summer representative day.
Abstract
Vegetated facade systems (VFS) have been used as green building envelope systems in recent years. Using VFS for ecological strategies and evaluating thermal performance of [...]
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Spatial variability of soil infiltration in the improvement and utilization area of aeolian sandy land in northwest Liaoning
L. Gang, L. Yaxi

Collection of Agricultural and Biological Sciences (2020). 1

Abstract
In order to study the characteristics of spatial variability of soil infiltration in the aeolian sandy land improvement and utilization area, this paper conducted a study on the six different land use types in the aeolian sandy land in northwest Liaoning by means of average and random distribution. With bare land as the control group, the physical parameters of the soil in the test area were analyzed and processed through traditional statistical analysis and geostatistical analysis, and the spatial distribution of various physical parameters was studied using ordinary Kriging interpolation. The results show that the bulk density of different land use types in the aeolian sandy land improvement and utilization area in northwestern Liaoning has been reduced, and the total porosity, capillary porosity, water content and the ratio of clay particles have increased to varying degrees. Soil infiltration has a negative correlation with moisture content and clay particles, and a positive correlation with the ratio of total porosity. In addition, among all types of improved utilization, other forest land has the largest infiltration and the research land has the smallest one.
Abstract
In order to study the characteristics of spatial variability of soil infiltration in the aeolian sandy land improvement and utilization area, this paper conducted a study [...]
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